<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:7d4cdb12-3477-44d0-baa2-d78f9fc8dbeb,g:be01a6c2-87da-4aa5-8e93-e26ea6bdd59f-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://fivestarbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUnaudited" xlink:type="simple" xlink:href="fsbc-20220630.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUnaudited"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUnaudited" xlink:type="extended" id="ic43ce44123fc4f088707b37fd7206d33_CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYUnaudited">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_f0d1f089-4e85-4be9-a52e-b63177c83f38" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_SharesOutstanding_f0d1f089-4e85-4be9-a52e-b63177c83f38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2fb99204-7144-4898-9d76-63389e93df6b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockholdersEquity_2fb99204-7144-4898-9d76-63389e93df6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_45b3574c-12ac-4322-9a80-d9af517c3fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_NetIncomeLoss_45b3574c-12ac-4322-9a80-d9af517c3fc9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_3acadcb4-6746-428d-a029-df6870e73e1c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_3acadcb4-6746-428d-a029-df6870e73e1c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_34a0f870-5c97-4585-954a-577fb9aeee34" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_34a0f870-5c97-4585-954a-577fb9aeee34" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_25f12bbb-75d1-4bc5-9381-1efa602d4892" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_25f12bbb-75d1-4bc5-9381-1efa602d4892" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_2fc79527-61de-47f1-93bd-7f36b9ef5750" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_2fc79527-61de-47f1-93bd-7f36b9ef5750" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_4f8b3812-e873-49aa-8e0e-f9d11986d6d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_4f8b3812-e873-49aa-8e0e-f9d11986d6d8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_APICShareBasedPaymentArrangementIncreaseForCostRecognitionInShares_bcab56b0-d37a-4298-958b-932cff4958d0" xlink:href="fsbc-20220630.xsd#fsbc_APICShareBasedPaymentArrangementIncreaseForCostRecognitionInShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_fsbc_APICShareBasedPaymentArrangementIncreaseForCostRecognitionInShares_bcab56b0-d37a-4298-958b-932cff4958d0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ab31afb7-531c-4779-adfe-ddb3ee7a2f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ab31afb7-531c-4779-adfe-ddb3ee7a2f7f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_aa239a0d-66c7-4776-9f5e-9bfdd0eb7e6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_aa239a0d-66c7-4776-9f5e-9bfdd0eb7e6f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_4eb6ff6c-fb26-4972-ac68-a876cf297ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_4eb6ff6c-fb26-4972-ac68-a876cf297ae6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalOther_49b383f7-156c-4ed6-8efc-df71daf336e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalOther_49b383f7-156c-4ed6-8efc-df71daf336e0" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList_a05cb8ce-b242-4900-88cb-7974108e1faa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_AccountingStandardsUpdateExtensibleList_a05cb8ce-b242-4900-88cb-7974108e1faa" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_305bd053-a711-486c-ad77-a5314e524951" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_DividendsCommonStock_305bd053-a711-486c-ad77-a5314e524951" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_aa13ce66-035d-4c20-9180-b5bec847d00d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_57888252-b39e-4db3-b3fd-3663d70e3599" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_2dfdc220-00e9-4b3d-aa66-e06014c151cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_df1f0d00-4291-4922-ab64-2286d622aa98" xlink:to="loc_us-gaap_StatementTable_2dfdc220-00e9-4b3d-aa66-e06014c151cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_0db5a918-c430-4da0-9fe5-1de80f5892c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2dfdc220-00e9-4b3d-aa66-e06014c151cf" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_0db5a918-c430-4da0-9fe5-1de80f5892c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0db5a918-c430-4da0-9fe5-1de80f5892c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_0db5a918-c430-4da0-9fe5-1de80f5892c6" xlink:to="loc_us-gaap_EquityComponentDomain_0db5a918-c430-4da0-9fe5-1de80f5892c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_03aede71-1369-440e-9fec-c2d9757dc758" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_0db5a918-c430-4da0-9fe5-1de80f5892c6" xlink:to="loc_us-gaap_EquityComponentDomain_03aede71-1369-440e-9fec-c2d9757dc758" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_0b3043e8-7cc4-4c99-a777-eabe4abbeabb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03aede71-1369-440e-9fec-c2d9757dc758" xlink:to="loc_us-gaap_CommonStockMember_0b3043e8-7cc4-4c99-a777-eabe4abbeabb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_a2fde7b5-211a-4d52-8370-6dbe56862af0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03aede71-1369-440e-9fec-c2d9757dc758" xlink:to="loc_us-gaap_RetainedEarningsMember_a2fde7b5-211a-4d52-8370-6dbe56862af0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2d66e588-cd2c-4c2f-a975-1fb1eff80738" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03aede71-1369-440e-9fec-c2d9757dc758" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2d66e588-cd2c-4c2f-a975-1fb1eff80738" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1f96d729-d057-43ea-b5e0-4affbdbd4753" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2dfdc220-00e9-4b3d-aa66-e06014c151cf" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1f96d729-d057-43ea-b5e0-4affbdbd4753" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1f96d729-d057-43ea-b5e0-4affbdbd4753_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1f96d729-d057-43ea-b5e0-4affbdbd4753" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1f96d729-d057-43ea-b5e0-4affbdbd4753_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ec676cc1-2a07-4344-9924-2f07ed7dc59f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1f96d729-d057-43ea-b5e0-4affbdbd4753" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ec676cc1-2a07-4344-9924-2f07ed7dc59f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_10dfac0c-489b-443f-bd06-43366e21b371" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ec676cc1-2a07-4344-9924-2f07ed7dc59f" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_10dfac0c-489b-443f-bd06-43366e21b371" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_6e322d29-b03f-4c45-aa68-ccd9f0369066" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2dfdc220-00e9-4b3d-aa66-e06014c151cf" xlink:to="loc_us-gaap_GranteeStatusAxis_6e322d29-b03f-4c45-aa68-ccd9f0369066" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_6e322d29-b03f-4c45-aa68-ccd9f0369066_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_6e322d29-b03f-4c45-aa68-ccd9f0369066" xlink:to="loc_us-gaap_GranteeStatusDomain_6e322d29-b03f-4c45-aa68-ccd9f0369066_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_d928b50c-6921-4e2a-ba07-94b3992f8747" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_6e322d29-b03f-4c45-aa68-ccd9f0369066" xlink:to="loc_us-gaap_GranteeStatusDomain_d928b50c-6921-4e2a-ba07-94b3992f8747" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_e22a53ac-5f0f-439d-9825-3e2e86db3f43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedPaymentArrangementEmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_d928b50c-6921-4e2a-ba07-94b3992f8747" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_e22a53ac-5f0f-439d-9825-3e2e86db3f43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_bf61acdf-636b-424b-ab7d-f1374ea00cda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedPaymentArrangementNonemployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_d928b50c-6921-4e2a-ba07-94b3992f8747" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_bf61acdf-636b-424b-ab7d-f1374ea00cda" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited" xlink:type="simple" xlink:href="fsbc-20220630.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited" xlink:type="extended" id="ie57de1746b984926a32d696d5058a2b6_CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_34d61145-ed76-4c3d-bd8c-8c25fe788fda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_34d61145-ed76-4c3d-bd8c-8c25fe788fda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_239cd5c9-6f5e-47f1-92a1-d275748f14ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_34d61145-ed76-4c3d-bd8c-8c25fe788fda" xlink:to="loc_us-gaap_NetIncomeLoss_239cd5c9-6f5e-47f1-92a1-d275748f14ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_7441737f-15c4-402d-98d0-839532851980" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_7441737f-15c4-402d-98d0-839532851980" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale_7939d9dd-1914-48ea-9932-a533203916ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale_7939d9dd-1914-48ea-9932-a533203916ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfLoansNet_3f6933c5-75d2-49a8-9d33-53a150f9dc22" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnSalesOfLoansNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_GainLossOnSalesOfLoansNet_3f6933c5-75d2-49a8-9d33-53a150f9dc22" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfLoansHeldForSale_acca85c1-36c6-47a2-9986-d2653540fa2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromSaleOfLoansHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_ProceedsFromSaleOfLoansHeldForSale_acca85c1-36c6-47a2-9986-d2653540fa2b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_59ef7a06-7e9b-4a91-9764-f4bd550078a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_59ef7a06-7e9b-4a91-9764-f4bd550078a6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankOwnedLifeInsuranceIncome_2be75058-9e42-44b8-8fc4-bfe7d7cf2ad9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BankOwnedLifeInsuranceIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_BankOwnedLifeInsuranceIncome_2be75058-9e42-44b8-8fc4-bfe7d7cf2ad9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_6e783461-094e-42d4-a99c-539466a5dbe7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_ShareBasedCompensation_6e783461-094e-42d4-a99c-539466a5dbe7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredLeasingFees_809ba9fe-92fa-4353-89ae-63aa32890a81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredLeasingFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredLeasingFees_809ba9fe-92fa-4353-89ae-63aa32890a81" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_158371c6-76ca-41c7-839d-bd5c41d59a83" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_158371c6-76ca-41c7-839d-bd5c41d59a83" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_55a45adf-3afc-4a6e-a838-a7caf974c557" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_55a45adf-3afc-4a6e-a838-a7caf974c557" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_aae0eb9c-2355-46ff-86b0-3e6ba4016ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_DepreciationAndAmortization_aae0eb9c-2355-46ff-86b0-3e6ba4016ca6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_671a08de-2757-4d69-8c23-cd2af183bf9f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_671a08de-2757-4d69-8c23-cd2af183bf9f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_4e2e88f2-dff3-4906-8b7f-04264c37b9f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_4e2e88f2-dff3-4906-8b7f-04264c37b9f2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_1ba3e523-67b2-48f2-9963-ec6a51d02e91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_db837b39-fa5a-4d62-b90d-d9d711bd1819" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_1ba3e523-67b2-48f2-9963-ec6a51d02e91" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_b11a7152-c09a-4e30-aa49-b1ed1779a45d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_b11a7152-c09a-4e30-aa49-b1ed1779a45d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet_003360e7-9991-4cb3-a37b-4e88c3d98569" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_b11a7152-c09a-4e30-aa49-b1ed1779a45d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet_003360e7-9991-4cb3-a37b-4e88c3d98569" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_3197994a-aceb-4026-a5de-a5fd4bc23c53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInInterestPayableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_b11a7152-c09a-4e30-aa49-b1ed1779a45d" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_3197994a-aceb-4026-a5de-a5fd4bc23c53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_88dafd36-2fd5-4d0e-ae5d-0f4f8d91d7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_b11a7152-c09a-4e30-aa49-b1ed1779a45d" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_88dafd36-2fd5-4d0e-ae5d-0f4f8d91d7d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_d68a754c-6d7a-4a97-ae70-9960b4482d75" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_d68a754c-6d7a-4a97-ae70-9960b4482d75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_109fe0e3-77d4-477f-bb73-e9e169b5e517" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_109fe0e3-77d4-477f-bb73-e9e169b5e517" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_1ccdb130-a166-4b38-9a45-bb6e90f8e48e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_1ccdb130-a166-4b38-9a45-bb6e90f8e48e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks_72bc1b60-b859-4acd-b2b7-b2cc48731945" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks_72bc1b60-b859-4acd-b2b7-b2cc48731945" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_PaymentsForOriginationOfLoansNetOfProceedsFromRepayments_703a3597-90b8-4329-8b45-ccfd63f3cd92" xlink:href="fsbc-20220630.xsd#fsbc_PaymentsForOriginationOfLoansNetOfProceedsFromRepayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_fsbc_PaymentsForOriginationOfLoansNetOfProceedsFromRepayments_703a3597-90b8-4329-8b45-ccfd63f3cd92" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_971e2a88-f28d-4ef8-8604-0b76b66e8c8a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_971e2a88-f28d-4ef8-8604-0b76b66e8c8a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock_65c2ac6e-a4a5-41be-be0b-ea4dd7840c1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock_65c2ac6e-a4a5-41be-be0b-ea4dd7840c1b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireLifeInsurancePolicies_20ef0f9a-2ef3-4ca2-86f5-11bd87fd4464" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireLifeInsurancePolicies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_PaymentsToAcquireLifeInsurancePolicies_20ef0f9a-2ef3-4ca2-86f5-11bd87fd4464" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_3e17e96b-779d-4a32-ae2f-324a7f0cbfaa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_d8515d8e-14ce-48f9-a234-5de348d75179" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_3e17e96b-779d-4a32-ae2f-324a7f0cbfaa" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeposits_87fbe52a-62e8-4722-b293-4511a8993b47" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_IncreaseDecreaseInDeposits_87fbe52a-62e8-4722-b293-4511a8993b47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_361637e4-017d-471d-a7cd-e87d3d9fab8f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_361637e4-017d-471d-a7cd-e87d3d9fab8f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromFederalHomeLoanBankBorrowings_3fda8c9e-3d93-4e26-945e-ad1ce8ddaf7d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromFederalHomeLoanBankBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_ProceedsFromFederalHomeLoanBankBorrowings_3fda8c9e-3d93-4e26-945e-ad1ce8ddaf7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_39f0ee20-f3e9-4b0e-84e3-e9754ad017c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_PaymentsOfDividends_39f0ee20-f3e9-4b0e-84e3-e9754ad017c1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_05125abf-4686-41fc-bc23-f5dae94039d1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_05125abf-4686-41fc-bc23-f5dae94039d1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_d4ca0e13-b214-40ae-97ae-45a40aa71e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_d4ca0e13-b214-40ae-97ae-45a40aa71e9d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_21fc8d20-77af-4711-8bd6-8978ed7ffd5d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_dfa340a9-5ebc-4285-b092-2b20e6a195fc" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_21fc8d20-77af-4711-8bd6-8978ed7ffd5d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_c06c598a-6dec-4379-b130-4118e4300859" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_1fbcc2ec-0caf-4f53-927b-3b8977b2e7a1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_1fbcc2ec-0caf-4f53-927b-3b8977b2e7a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_67e39494-350a-47e6-b4f0-6f1babb71526" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_1fbcc2ec-0caf-4f53-927b-3b8977b2e7a1" xlink:to="loc_us-gaap_InterestPaidNet_67e39494-350a-47e6-b4f0-6f1babb71526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_faa0452d-9cd4-4250-8768-8fd42c724af8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_1fbcc2ec-0caf-4f53-927b-3b8977b2e7a1" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_faa0452d-9cd4-4250-8768-8fd42c724af8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_TransferFromLoansHeldForInvestmentToLoansHeldForSale_9b39d88e-361f-4796-8972-53d54b24dad3" xlink:href="fsbc-20220630.xsd#fsbc_TransferFromLoansHeldForInvestmentToLoansHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:to="loc_fsbc_TransferFromLoansHeldForInvestmentToLoansHeldForSale_9b39d88e-361f-4796-8972-53d54b24dad3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments_13d7066e-ae18-4a8c-8308-38e5f4f74d29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:to="loc_us-gaap_UnrealizedGainLossOnInvestments_13d7066e-ae18-4a8c-8308-38e5f4f74d29" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred_221b3237-fd37-4c19-9d3c-6f610a78a97c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:to="loc_us-gaap_CapitalLeaseObligationsIncurred_221b3237-fd37-4c19-9d3c-6f610a78a97c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_4e02578d-5456-444a-8b5b-71f94fc68987" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_4e02578d-5456-444a-8b5b-71f94fc68987" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_6c5fecad-37be-49aa-bc50-cc1c129b259e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_25ac86c1-f745-4208-ab23-56a58389a321" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_6c5fecad-37be-49aa-bc50-cc1c129b259e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_947a69c5-5cdf-4d1c-926b-5d7a698fe765" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ed199e23-ec69-413d-a4a4-b279b88b6810" xlink:to="loc_us-gaap_StatementTable_947a69c5-5cdf-4d1c-926b-5d7a698fe765" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_97784461-6097-4036-a582-2d4af193ac32" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_947a69c5-5cdf-4d1c-926b-5d7a698fe765" xlink:to="loc_us-gaap_GranteeStatusAxis_97784461-6097-4036-a582-2d4af193ac32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_97784461-6097-4036-a582-2d4af193ac32_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_97784461-6097-4036-a582-2d4af193ac32" xlink:to="loc_us-gaap_GranteeStatusDomain_97784461-6097-4036-a582-2d4af193ac32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_c45a33f5-9a71-42df-a9a2-e026fecf1c57" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_97784461-6097-4036-a582-2d4af193ac32" xlink:to="loc_us-gaap_GranteeStatusDomain_c45a33f5-9a71-42df-a9a2-e026fecf1c57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_bccc0670-db09-45c5-b761-a8bf23186b09" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedPaymentArrangementEmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_c45a33f5-9a71-42df-a9a2-e026fecf1c57" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_bccc0670-db09-45c5-b761-a8bf23186b09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_fe559b6c-23f6-43ef-a1fc-f3e3b8ebca1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedPaymentArrangementNonemployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_c45a33f5-9a71-42df-a9a2-e026fecf1c57" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_fe559b6c-23f6-43ef-a1fc-f3e3b8ebca1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_5a12e589-9726-48b8-bb75-3632113951c4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_947a69c5-5cdf-4d1c-926b-5d7a698fe765" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_5a12e589-9726-48b8-bb75-3632113951c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5a12e589-9726-48b8-bb75-3632113951c4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_5a12e589-9726-48b8-bb75-3632113951c4" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5a12e589-9726-48b8-bb75-3632113951c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_daa7be4d-7467-4102-8f9f-fcb15e4fb940" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_5a12e589-9726-48b8-bb75-3632113951c4" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_daa7be4d-7467-4102-8f9f-fcb15e4fb940" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602CumulativeEffectPeriodOfAdoptionMember_96349db9-5a62-4d01-8a21-b989f3613704" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdate201602CumulativeEffectPeriodOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_daa7be4d-7467-4102-8f9f-fcb15e4fb940" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602CumulativeEffectPeriodOfAdoptionMember_96349db9-5a62-4d01-8a21-b989f3613704" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/BasisofPresentationNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#BasisofPresentationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/BasisofPresentationNarrativeDetails" xlink:type="extended" id="i3fdcd195a46449528ce58c6827d166cc_BasisofPresentationNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiarySaleOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommonStockConvertibleSharesIssuable_abe7316c-3974-421f-9a47-7bcd298f878e" xlink:href="fsbc-20220630.xsd#fsbc_CommonStockConvertibleSharesIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_fsbc_CommonStockConvertibleSharesIssuable_abe7316c-3974-421f-9a47-7bcd298f878e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfBranchOffices_4dd842f3-d115-45ba-8216-d7b371fc1376" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfBranchOffices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_fsbc_NumberOfBranchOffices_4dd842f3-d115-45ba-8216-d7b371fc1376" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfLoanProductionOffices_2c4ada0d-8e6d-46b8-9f8a-9c4df1c641e3" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfLoanProductionOffices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_fsbc_NumberOfLoanProductionOffices_2c4ada0d-8e6d-46b8-9f8a-9c4df1c641e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_9133face-16a4-4c27-b5b2-090a9c289947" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_9133face-16a4-4c27-b5b2-090a9c289947" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_ec1f3b81-9da3-4639-a339-48043fe2dfd9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_ec1f3b81-9da3-4639-a339-48043fe2dfd9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceInitialPublicOffering_4012ea03-4fd6-48eb-a867-325f380b274e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceInitialPublicOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_ProceedsFromIssuanceInitialPublicOffering_4012ea03-4fd6-48eb-a867-325f380b274e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_5ab2417f-9edf-4dbb-a42f-1b7eb3cdc7da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_5ab2417f-9edf-4dbb-a42f-1b7eb3cdc7da" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_a155cd49-43f1-4841-a444-0170295c7d46" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_NumberOfReportableSegments_a155cd49-43f1-4841-a444-0170295c7d46" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ProFormaTaxRate_1ea3df4a-2a9e-48d2-9862-a5a1c9bcf8b6" xlink:href="fsbc-20220630.xsd#fsbc_ProFormaTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_fsbc_ProFormaTaxRate_1ea3df4a-2a9e-48d2-9862-a5a1c9bcf8b6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_1560d7f3-a56e-4dcf-a440-29b754ac4180" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_7b5fe8f0-a235-458e-a6e9-698c5ef8fb53" xlink:to="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_1560d7f3-a56e-4dcf-a440-29b754ac4180" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_3c0c35f4-094c-49d9-bb93-dcb590be91c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_1560d7f3-a56e-4dcf-a440-29b754ac4180" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_3c0c35f4-094c-49d9-bb93-dcb590be91c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_3c0c35f4-094c-49d9-bb93-dcb590be91c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_3c0c35f4-094c-49d9-bb93-dcb590be91c0" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_3c0c35f4-094c-49d9-bb93-dcb590be91c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_03ebe14a-29a0-4fdd-90f2-45f3af0c2aef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_3c0c35f4-094c-49d9-bb93-dcb590be91c0" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_03ebe14a-29a0-4fdd-90f2-45f3af0c2aef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_e917ca1d-9112-4336-a373-8c03199bcb7c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_03ebe14a-29a0-4fdd-90f2-45f3af0c2aef" xlink:to="loc_us-gaap_IPOMember_e917ca1d-9112-4336-a373-8c03199bcb7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OverAllotmentOptionMember_c1f469eb-a01b-4dfe-8f3c-de7ed12827da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OverAllotmentOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_03ebe14a-29a0-4fdd-90f2-45f3af0c2aef" xlink:to="loc_us-gaap_OverAllotmentOptionMember_c1f469eb-a01b-4dfe-8f3c-de7ed12827da" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/FairValueofAssetsandLiabilitiesFairValueofAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#FairValueofAssetsandLiabilitiesFairValueofAssetsandLiabilitiesMeasuredonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/FairValueofAssetsandLiabilitiesFairValueofAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="extended" id="ia79bc3e1b818473e999010c268589006_FairValueofAssetsandLiabilitiesFairValueofAssetsandLiabilitiesMeasuredonRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_efa2b56b-00e5-4867-b684-7592565ac6a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5a0589f4-41fd-4530-9e9e-eec44f01b205" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_efa2b56b-00e5-4867-b684-7592565ac6a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5a0589f4-41fd-4530-9e9e-eec44f01b205" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_7121adf4-362f-47bd-bb8f-fc713b5e2a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_efa2b56b-00e5-4867-b684-7592565ac6a4" xlink:to="loc_us-gaap_DerivativeAssets_7121adf4-362f-47bd-bb8f-fc713b5e2a8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_c66ed027-1dac-4803-b74b-084a856581f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_efa2b56b-00e5-4867-b684-7592565ac6a4" xlink:to="loc_us-gaap_DerivativeLiabilities_c66ed027-1dac-4803-b74b-084a856581f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_efa2b56b-00e5-4867-b684-7592565ac6a4" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d2f25dfc-c30b-4876-aa2f-38cde759dcb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_4b82c55f-5a28-4233-acb2-7be8a6fd3ff7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d2f25dfc-c30b-4876-aa2f-38cde759dcb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsTotalMember_95a239d7-beb8-4dfc-a6b7-300609262ef0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d2f25dfc-c30b-4876-aa2f-38cde759dcb3" xlink:to="loc_us-gaap_AssetsTotalMember_95a239d7-beb8-4dfc-a6b7-300609262ef0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesTotalMember_9fc5c0fb-bbdd-4d7e-a2c6-fa9b9d7e0420" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d2f25dfc-c30b-4876-aa2f-38cde759dcb3" xlink:to="loc_us-gaap_LiabilitiesTotalMember_9fc5c0fb-bbdd-4d7e-a2c6-fa9b9d7e0420" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_feca9c76-0f3b-439b-8a37-c08e29b0af4b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_abc3d5e9-d6f9-493f-91c0-1fcf1e0f790b" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_feca9c76-0f3b-439b-8a37-c08e29b0af4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_482b272f-ff8b-479e-97b3-4d2547013489" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_feca9c76-0f3b-439b-8a37-c08e29b0af4b" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_482b272f-ff8b-479e-97b3-4d2547013489" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_ff689425-6578-4a54-a2f9-92eee8850209" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_feca9c76-0f3b-439b-8a37-c08e29b0af4b" xlink:to="loc_us-gaap_InterestRateSwapMember_ff689425-6578-4a54-a2f9-92eee8850209" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_f36620bb-7cf0-4072-a5eb-e1908236076a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c510cd4b-d126-43cd-a5b4-5ea38f8c46ac" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_f36620bb-7cf0-4072-a5eb-e1908236076a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_9032115d-85f6-425b-b311-b0c7c13df4da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_f36620bb-7cf0-4072-a5eb-e1908236076a" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_9032115d-85f6-425b-b311-b0c7c13df4da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99d1099b-fd49-44ef-8b4e-d34febd7c411" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2a8ee0da-7d96-4361-9607-1327b47dcc0d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99d1099b-fd49-44ef-8b4e-d34febd7c411" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_99d1099b-fd49-44ef-8b4e-d34febd7c411_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99d1099b-fd49-44ef-8b4e-d34febd7c411" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_99d1099b-fd49-44ef-8b4e-d34febd7c411_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_87310360-f076-40a2-b339-bde72f256598" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99d1099b-fd49-44ef-8b4e-d34febd7c411" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_87310360-f076-40a2-b339-bde72f256598" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_2950fd7c-091b-4d20-a95f-48126f271eac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_87310360-f076-40a2-b339-bde72f256598" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_2950fd7c-091b-4d20-a95f-48126f271eac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_ef22dfb9-8607-4d65-a181-e2cb10e3c3aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_87310360-f076-40a2-b339-bde72f256598" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_ef22dfb9-8607-4d65-a181-e2cb10e3c3aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_ca2a5f31-ecd7-4442-b2c9-fdecd9e60afc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_87310360-f076-40a2-b339-bde72f256598" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_ca2a5f31-ecd7-4442-b2c9-fdecd9e60afc" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/FairValueofAssetsandLiabilitiesFairValueEstimatesforFinancialInstrumentsbyBalanceSheetGroupingDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#FairValueofAssetsandLiabilitiesFairValueEstimatesforFinancialInstrumentsbyBalanceSheetGroupingDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/FairValueofAssetsandLiabilitiesFairValueEstimatesforFinancialInstrumentsbyBalanceSheetGroupingDetails" xlink:type="extended" id="ia470c5d2f5f747919de612d7bfd8b7ab_FairValueofAssetsandLiabilitiesFairValueEstimatesforFinancialInstrumentsbyBalanceSheetGroupingDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_7bb51c4c-7d76-4199-a37d-47302d156415" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:href="fsbc-20220630.xsd#fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_7bb51c4c-7d76-4199-a37d-47302d156415" xlink:to="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_b89f0e0a-c7b6-452f-ad5c-912ea05814bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_b89f0e0a-c7b6-452f-ad5c-912ea05814bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_TimeDepositAtFairValueDisclosure_4253bfbb-1968-4878-9b22-3d80fc66d143" xlink:href="fsbc-20220630.xsd#fsbc_TimeDepositAtFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_fsbc_TimeDepositAtFairValueDisclosure_4253bfbb-1968-4878-9b22-3d80fc66d143" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_d73edbb4-2821-4d9a-86ee-45b244378065" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_d73edbb4-2821-4d9a-86ee-45b244378065" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_f6decf04-4202-4b06-8107-91047778b287" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_f6decf04-4202-4b06-8107-91047778b287" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_8edd8f16-5e1a-454f-b361-544c57ed98a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansHeldForSaleFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_8edd8f16-5e1a-454f-b361-544c57ed98a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_c1a0998e-fd68-4b0b-ad6d-0231ebd46908" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_c1a0998e-fd68-4b0b-ad6d-0231ebd46908" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure_f18a2485-1adc-41da-a278-510da7b1c51b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure_f18a2485-1adc-41da-a278-510da7b1c51b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableFairValueDisclosure_73c938e4-2a8e-4f05-8adb-3e971bd30b29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_AccountsReceivableFairValueDisclosure_73c938e4-2a8e-4f05-8adb-3e971bd30b29" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_4b771d43-df17-4064-ad4f-5896cf765882" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialAssetsRecordedAtAmortizedCostAbstract_813f8079-255d-46da-a5b9-a069bb14bb76" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_4b771d43-df17-4064-ad4f-5896cf765882" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:href="fsbc-20220630.xsd#fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_7bb51c4c-7d76-4199-a37d-47302d156415" xlink:to="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsFairValueDisclosure_22dfa230-944f-459c-a368-2b15bd45891e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepositsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:to="loc_us-gaap_DepositsFairValueDisclosure_22dfa230-944f-459c-a368-2b15bd45891e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableFairValueDisclosure_6155bbfc-13bb-4472-865d-f41a78fa78af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:to="loc_us-gaap_AccountsPayableFairValueDisclosure_6155bbfc-13bb-4472-865d-f41a78fa78af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_3ff4c7bb-aa12-4b2b-8508-96c7f1aa846a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_3ff4c7bb-aa12-4b2b-8508-96c7f1aa846a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations_29f007a5-13ca-4b07-a2cf-f1a6cf8f390e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FinancialLiabilitiesRecordedAtAmortizedCostAbstract_72745b35-3c90-4590-8d42-12e1cbc37d0e" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations_29f007a5-13ca-4b07-a2cf-f1a6cf8f390e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_3ea37acf-3219-497d-9b62-5c824b29d6d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_7bb51c4c-7d76-4199-a37d-47302d156415" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_3ea37acf-3219-497d-9b62-5c824b29d6d9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_8d1dc93c-4356-42ce-b399-2ca4687e7dc6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_3ea37acf-3219-497d-9b62-5c824b29d6d9" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_8d1dc93c-4356-42ce-b399-2ca4687e7dc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8d1dc93c-4356-42ce-b399-2ca4687e7dc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_8d1dc93c-4356-42ce-b399-2ca4687e7dc6" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8d1dc93c-4356-42ce-b399-2ca4687e7dc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ff7ee894-1016-49d8-bd4a-d6938faddcdd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_8d1dc93c-4356-42ce-b399-2ca4687e7dc6" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ff7ee894-1016-49d8-bd4a-d6938faddcdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cd71981b-dad5-49cf-84e8-5e320f8e7513" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ff7ee894-1016-49d8-bd4a-d6938faddcdd" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_cd71981b-dad5-49cf-84e8-5e320f8e7513" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_4b0df9f6-66c7-4895-85d6-0a5b3db87b73" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ff7ee894-1016-49d8-bd4a-d6938faddcdd" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_4b0df9f6-66c7-4895-85d6-0a5b3db87b73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_62c71efa-b0a8-49dd-aae7-892cebb8567c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_ff7ee894-1016-49d8-bd4a-d6938faddcdd" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_62c71efa-b0a8-49dd-aae7-892cebb8567c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_3ea37acf-3219-497d-9b62-5c824b29d6d9" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5d7d4d90-098c-4585-b37c-579ba33a7870" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_c724f7e3-b7d8-4424-b2bc-b2dbb9584ec9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5d7d4d90-098c-4585-b37c-579ba33a7870" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_3542009a-9935-403a-94c4-e6bba86c8e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5d7d4d90-098c-4585-b37c-579ba33a7870" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_3542009a-9935-403a-94c4-e6bba86c8e9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_971dd38a-5063-4bc9-bc61-d0b9c1e7e745" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5d7d4d90-098c-4585-b37c-579ba33a7870" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_971dd38a-5063-4bc9-bc61-d0b9c1e7e745" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_d827f32c-5b71-4562-b6f1-7e52da21c556" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5d7d4d90-098c-4585-b37c-579ba33a7870" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_d827f32c-5b71-4562-b6f1-7e52da21c556" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesHeldtomaturityDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesHeldtomaturityDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesHeldtomaturityDetails" xlink:type="extended" id="i1e543eb14dac42fa9e30f07c94e3bd5e_InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesHeldtomaturityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecurities_4711fc83-5546-4da0-b886-85ca4ecfe6a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:to="loc_us-gaap_HeldToMaturitySecurities_4711fc83-5546-4da0-b886-85ca4ecfe6a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_HeldToMaturitySecuritiesGrossUnrealizedGains_595d499f-c0c8-4791-8ffa-6f2f3eb501f4" xlink:href="fsbc-20220630.xsd#fsbc_HeldToMaturitySecuritiesGrossUnrealizedGains"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:to="loc_fsbc_HeldToMaturitySecuritiesGrossUnrealizedGains_595d499f-c0c8-4791-8ffa-6f2f3eb501f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_HeldToMaturitySecuritiesGrossUnrealizedLoss_bd7591c2-6e1d-4c11-a1f4-6bc492bc8c9e" xlink:href="fsbc-20220630.xsd#fsbc_HeldToMaturitySecuritiesGrossUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:to="loc_fsbc_HeldToMaturitySecuritiesGrossUnrealizedLoss_bd7591c2-6e1d-4c11-a1f4-6bc492bc8c9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_3a1f7760-8fb0-456f-8777-b4d6e14ed65a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_3a1f7760-8fb0-456f-8777-b4d6e14ed65a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_a01de472-f258-4f7d-b894-cd3910fe48f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_559a0098-9a6e-4796-b23d-0ddfe841eef7" xlink:to="loc_us-gaap_MarketableSecuritiesTable_a01de472-f258-4f7d-b894-cd3910fe48f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_df5918dd-6141-4735-ba62-a025a727dd7c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_a01de472-f258-4f7d-b894-cd3910fe48f0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_df5918dd-6141-4735-ba62-a025a727dd7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_df5918dd-6141-4735-ba62-a025a727dd7c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_df5918dd-6141-4735-ba62-a025a727dd7c" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_df5918dd-6141-4735-ba62-a025a727dd7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_21ed62b9-fc1a-432e-868a-3b90c1cef9f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_df5918dd-6141-4735-ba62-a025a727dd7c" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_21ed62b9-fc1a-432e-868a-3b90c1cef9f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_fee02aac-8995-4a2c-bdf1-48dd52d1a619" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_21ed62b9-fc1a-432e-868a-3b90c1cef9f0" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_fee02aac-8995-4a2c-bdf1-48dd52d1a619" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesAvailableforsaleDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesAvailableforsaleDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesAvailableforsaleDetails" xlink:type="extended" id="i15f8c8e8b7dc434b82086cf6e79f9d61_InvestmentSecuritiesAmortizedCostandFairValueofSecuritiesAvailableforsaleDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_ece2f2ea-8d00-439d-8d90-bca1030cc17f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_ece2f2ea-8d00-439d-8d90-bca1030cc17f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_e3460cef-4885-4c6e-8b74-eaca601bbfe7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_e3460cef-4885-4c6e-8b74-eaca601bbfe7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_11ae5338-2605-4858-90d7-2b54054997cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_11ae5338-2605-4858-90d7-2b54054997cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_878df22d-e11e-4974-a801-2093f6c535fb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_878df22d-e11e-4974-a801-2093f6c535fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_e073d52d-a831-4480-948a-666b6afd1c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_15b330e0-4f57-4bfe-a8d6-dbbec538df46" xlink:to="loc_us-gaap_MarketableSecuritiesTable_e073d52d-a831-4480-948a-666b6afd1c6a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_d9ed7947-b49a-4276-8a5a-229e788183f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_e073d52d-a831-4480-948a-666b6afd1c6a" xlink:to="loc_us-gaap_FinancialInstrumentAxis_d9ed7947-b49a-4276-8a5a-229e788183f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d9ed7947-b49a-4276-8a5a-229e788183f6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d9ed7947-b49a-4276-8a5a-229e788183f6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d9ed7947-b49a-4276-8a5a-229e788183f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d9ed7947-b49a-4276-8a5a-229e788183f6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_af099ed1-29c8-49ee-9c01-be63e18feaf1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_af099ed1-29c8-49ee-9c01-be63e18feaf1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_382eaf00-0c8d-44d5-93b5-d68405f76222" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_382eaf00-0c8d-44d5-93b5-d68405f76222" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_e8a7713c-fba8-4f1c-96f8-4205e0827f7c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_e8a7713c-fba8-4f1c-96f8-4205e0827f7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedDebtObligationsMember_dbc7706b-e146-4f1a-89bd-0be2c2604dde" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CollateralizedDebtObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:to="loc_us-gaap_CollateralizedDebtObligationsMember_dbc7706b-e146-4f1a-89bd-0be2c2604dde" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_3200a869-d206-4b66-8a0e-082efb99626a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_15cdcce7-9472-4700-8bc0-d6b17a6168f0" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_3200a869-d206-4b66-8a0e-082efb99626a" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofInvestmentDebtSecuritiesbyContractualMaturityDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesAmortizedCostandFairValueofInvestmentDebtSecuritiesbyContractualMaturityDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesAmortizedCostandFairValueofInvestmentDebtSecuritiesbyContractualMaturityDetails" xlink:type="extended" id="i0fa42dd42db7496fb69819c4d08fe68e_InvestmentSecuritiesAmortizedCostandFairValueofInvestmentDebtSecuritiesbyContractualMaturityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAbstract_159d669d-5470-462d-ad44-5af40707a7e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAbstract_159d669d-5470-462d-ad44-5af40707a7e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAbstract_159d669d-5470-462d-ad44-5af40707a7e9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount_790fb842-e100-4ad8-92d3-4e2ee380f18a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount_790fb842-e100-4ad8-92d3-4e2ee380f18a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_f3e7a098-054f-482a-9dcf-a2f8f71821c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_f3e7a098-054f-482a-9dcf-a2f8f71821c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_42c5ab6d-44b1-4b69-968b-061b7eed8114" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_42c5ab6d-44b1-4b69-968b-061b7eed8114" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount_58ffae9f-8107-47e6-bec1-5f50aa2ff56f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_c9d9acc0-db8f-4062-addf-7960847db3eb" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount_58ffae9f-8107-47e6-bec1-5f50aa2ff56f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAbstract_159d669d-5470-462d-ad44-5af40707a7e9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue_f8e4973c-5819-4304-950e-033f447425af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue_f8e4973c-5819-4304-950e-033f447425af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_e17cc4cb-18f7-40e0-9de7-ca16073061b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_e17cc4cb-18f7-40e0-9de7-ca16073061b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_834e2ad5-7a77-47ce-b5a4-ef76b12e00c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_834e2ad5-7a77-47ce-b5a4-ef76b12e00c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue_03cdf4e2-b30d-4432-86a7-bd2a9a9a5ad7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValueAbstract_286ae5fe-e2f0-4c3c-8926-67a9288c462e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue_03cdf4e2-b30d-4432-86a7-bd2a9a9a5ad7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract_860d0040-b6f3-47d6-97df-12c1b1554564" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract_860d0040-b6f3-47d6-97df-12c1b1554564" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract_860d0040-b6f3-47d6-97df-12c1b1554564" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_14937704-604c-4cd5-a58d-b9e8a6e14bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_14937704-604c-4cd5-a58d-b9e8a6e14bd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_770effe5-8e68-4ec8-a777-7ba08e9d431e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_770effe5-8e68-4ec8-a777-7ba08e9d431e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_951291e8-818b-4eb7-a182-59f024786e8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_951291e8-818b-4eb7-a182-59f024786e8e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_d0d52917-f3f7-4cec-b1f0-839ced4e65cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasisAbstract_0ec5cc07-ea4c-4f29-8a6e-68fc1a610bcc" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_d0d52917-f3f7-4cec-b1f0-839ced4e65cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAbstract_860d0040-b6f3-47d6-97df-12c1b1554564" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_5383afba-935e-4065-b98b-a4d0a37a2f43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_5383afba-935e-4065-b98b-a4d0a37a2f43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_c89dd851-0d25-401f-b40e-7e6a4523ec1f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_c89dd851-0d25-401f-b40e-7e6a4523ec1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_2c5f51d5-8943-4bd6-a87e-59199b72e615" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_2c5f51d5-8943-4bd6-a87e-59199b72e615" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_2af7746a-999c-4ad8-add8-dca1063e7465" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAbstract_04127be5-43c4-4a0b-959e-76b6a7163a92" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_2af7746a-999c-4ad8-add8-dca1063e7465" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecurities_3701b197-b2e6-4622-a3bd-6aed0438609c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_HeldToMaturitySecurities_3701b197-b2e6-4622-a3bd-6aed0438609c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_7794ddf4-2490-4dcb-bb47-0994ab875734" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_7794ddf4-2490-4dcb-bb47-0994ab875734" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_cb2eacb3-6530-46fc-94b9-e443942a84ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_cb2eacb3-6530-46fc-94b9-e443942a84ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_61b8834e-9444-4ca5-bcfc-1ff12c667e70" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_61b8834e-9444-4ca5-bcfc-1ff12c667e70" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_6ab5f553-1f7a-4a26-827b-3c1caa971227" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_fabadc6e-d036-47e3-af14-ae18b871c4e4" xlink:to="loc_us-gaap_MarketableSecuritiesTable_6ab5f553-1f7a-4a26-827b-3c1caa971227" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_dcbded8d-2b05-434d-83ca-5a9bdbeef552" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_6ab5f553-1f7a-4a26-827b-3c1caa971227" xlink:to="loc_us-gaap_FinancialInstrumentAxis_dcbded8d-2b05-434d-83ca-5a9bdbeef552" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcbded8d-2b05-434d-83ca-5a9bdbeef552_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_dcbded8d-2b05-434d-83ca-5a9bdbeef552" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcbded8d-2b05-434d-83ca-5a9bdbeef552_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_dcbded8d-2b05-434d-83ca-5a9bdbeef552" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_4c08b021-a7a8-4d92-93ff-73f4d495aeb2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_4c08b021-a7a8-4d92-93ff-73f4d495aeb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_cd0a24fb-9f71-4f92-bddc-d6f6ef41bf81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_cd0a24fb-9f71-4f92-bddc-d6f6ef41bf81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedDebtObligationsMember_87f8af49-3c42-4cc4-9969-fda8bd77c7a0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CollateralizedDebtObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:to="loc_us-gaap_CollateralizedDebtObligationsMember_87f8af49-3c42-4cc4-9969-fda8bd77c7a0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_d8725443-cb40-4951-b00a-aa57938adeef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_98592805-750a-4480-bcce-5a07d226f116" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_d8725443-cb40-4951-b00a-aa57938adeef" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesPledgedInvestmentSecuritiesDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesPledgedInvestmentSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesPledgedInvestmentSecuritiesDetails" xlink:type="extended" id="icb08d901b93a494eb21cfc5b077937b4_InvestmentSecuritiesPledgedInvestmentSecuritiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_157a9f0e-8877-48d6-91a3-455d8307c80e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedAssetsSeparatelyReportedMortgageRelatedSecuritiesAvailableForSaleOrHeldForInvestment_b448e6bf-e513-4a55-b012-cbb97bf4d684" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PledgedAssetsSeparatelyReportedMortgageRelatedSecuritiesAvailableForSaleOrHeldForInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_157a9f0e-8877-48d6-91a3-455d8307c80e" xlink:to="loc_us-gaap_PledgedAssetsSeparatelyReportedMortgageRelatedSecuritiesAvailableForSaleOrHeldForInvestment_b448e6bf-e513-4a55-b012-cbb97bf4d684" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_0eb7e8e3-74cf-4132-9b81-d5f281a24406" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_157a9f0e-8877-48d6-91a3-455d8307c80e" xlink:to="loc_us-gaap_MarketableSecuritiesTable_0eb7e8e3-74cf-4132-9b81-d5f281a24406" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_60f08f29-18f9-43aa-b751-49a382901a52" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_0eb7e8e3-74cf-4132-9b81-d5f281a24406" xlink:to="loc_srt_StatementGeographicalAxis_60f08f29-18f9-43aa-b751-49a382901a52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_60f08f29-18f9-43aa-b751-49a382901a52_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_60f08f29-18f9-43aa-b751-49a382901a52" xlink:to="loc_srt_SegmentGeographicalDomain_60f08f29-18f9-43aa-b751-49a382901a52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_02573298-2eb0-4745-95e3-e630545850e6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_60f08f29-18f9-43aa-b751-49a382901a52" xlink:to="loc_srt_SegmentGeographicalDomain_02573298-2eb0-4745-95e3-e630545850e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_de16d337-ba8c-4db3-844d-0dd2c69768bf" xlink:href="https://xbrl.sec.gov/stpr/2021/stpr-2021.xsd#stpr_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_02573298-2eb0-4745-95e3-e630545850e6" xlink:to="loc_stpr_CA_de16d337-ba8c-4db3-844d-0dd2c69768bf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesAvailableforsaleSecuritiesinaContinuousUnrealizedLossPositionDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesAvailableforsaleSecuritiesinaContinuousUnrealizedLossPositionDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesAvailableforsaleSecuritiesinaContinuousUnrealizedLossPositionDetails" xlink:type="extended" id="iebcdcc96122748478a6d6411bb0ce996_InvestmentSecuritiesAvailableforsaleSecuritiesinaContinuousUnrealizedLossPositionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_5686fa3f-9c77-4560-8ba4-182850c83603" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_5686fa3f-9c77-4560-8ba4-182850c83603" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_b81099c3-1c0e-4999-8fc9-0f327f789b95" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_b81099c3-1c0e-4999-8fc9-0f327f789b95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerFairValue_f52f3f68-3159-44ca-b79b-3bc4a24ef228" xlink:href="fsbc-20220630.xsd#fsbc_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_fsbc_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerFairValue_f52f3f68-3159-44ca-b79b-3bc4a24ef228" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_6419b390-f9c0-41f6-ba61-619ec98bee63" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_6419b390-f9c0-41f6-ba61-619ec98bee63" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValue_44989ee0-92d2-4f37-8cb0-ff3677162625" xlink:href="fsbc-20220630.xsd#fsbc_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_fsbc_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValue_44989ee0-92d2-4f37-8cb0-ff3677162625" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_04d770f4-db5e-42d1-a1bb-48b2f7a463fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_04d770f4-db5e-42d1-a1bb-48b2f7a463fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_a70bf021-3b3d-4bef-bc2b-a9b4e9385dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_abe889ad-d4db-466e-9664-a3bf814b6777" xlink:to="loc_us-gaap_MarketableSecuritiesTable_a70bf021-3b3d-4bef-bc2b-a9b4e9385dcb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_a70bf021-3b3d-4bef-bc2b-a9b4e9385dcb" xlink:to="loc_us-gaap_FinancialInstrumentAxis_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_bdb60a9d-5a8a-4c0f-8970-62ef74ca1b51" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_d9107af6-a3a0-40f2-85cb-d24d02d02da4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_d9107af6-a3a0-40f2-85cb-d24d02d02da4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_7a6c13af-48c8-4d5d-8a0f-513ab9ceec34" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_7a6c13af-48c8-4d5d-8a0f-513ab9ceec34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_d7a36e3c-4b22-47f6-85d1-1580b56816d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_d7a36e3c-4b22-47f6-85d1-1580b56816d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedDebtObligationsMember_0cc8cb22-0b79-4b20-883e-7e26c22d66e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CollateralizedDebtObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:to="loc_us-gaap_CollateralizedDebtObligationsMember_0cc8cb22-0b79-4b20-883e-7e26c22d66e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_4346dcac-3994-477c-bea9-081fd70c5ba9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9da57b64-84a8-4a85-aaec-e71604d87126" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_4346dcac-3994-477c-bea9-081fd70c5ba9" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InvestmentSecuritiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="extended" id="i324e26512c9c47939115b667bdc3575f_InvestmentSecuritiesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_e94d236e-813b-4076-b06e-d28bff3a9261" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_e94d236e-813b-4076-b06e-d28bff3a9261" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_0f6078c4-6357-4ff2-a0b3-5064f2895cda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_0f6078c4-6357-4ff2-a0b3-5064f2895cda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_6ccf7ee4-41e1-4b24-808b-b44699104015" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_6ccf7ee4-41e1-4b24-808b-b44699104015" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_b406e8b2-fd0b-4712-bf03-124bcba6ac13" xlink:href="fsbc-20220630.xsd#fsbc_DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_fsbc_DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_b406e8b2-fd0b-4712-bf03-124bcba6ac13" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalHomeLoanBankAdvancesStockPriceForSalesAndPurchases_263c2842-0d31-4bd0-9fdd-b7efbe0ee3d8" xlink:href="fsbc-20220630.xsd#fsbc_FederalHomeLoanBankAdvancesStockPriceForSalesAndPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_fsbc_FederalHomeLoanBankAdvancesStockPriceForSalesAndPurchases_263c2842-0d31-4bd0-9fdd-b7efbe0ee3d8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankStock_b192a4ca-60a5-4992-91a4-2bd179a59d7a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FederalHomeLoanBankStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_us-gaap_FederalHomeLoanBankStock_b192a4ca-60a5-4992-91a4-2bd179a59d7a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalHomeLoanBankStockAnnualizedDividendRatePercentage_a48761c0-9b99-4539-a326-b5443876dbaf" xlink:href="fsbc-20220630.xsd#fsbc_FederalHomeLoanBankStockAnnualizedDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_fsbc_FederalHomeLoanBankStockAnnualizedDividendRatePercentage_a48761c0-9b99-4539-a326-b5443876dbaf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalHomeLoanBankStockDividends_10cefc31-6001-4ef5-ac33-1efa1b57ecea" xlink:href="fsbc-20220630.xsd#fsbc_FederalHomeLoanBankStockDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_fsbc_FederalHomeLoanBankStockDividends_10cefc31-6001-4ef5-ac33-1efa1b57ecea" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_e625748a-442c-4332-bf42-b0f6b11386ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_7ce9a5da-9f08-4253-80f0-dd54f35af74b" xlink:to="loc_us-gaap_MarketableSecuritiesTable_e625748a-442c-4332-bf42-b0f6b11386ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_3125b111-85cd-4ce3-81d8-addfb0fdcee8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_e625748a-442c-4332-bf42-b0f6b11386ea" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_3125b111-85cd-4ce3-81d8-addfb0fdcee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3125b111-85cd-4ce3-81d8-addfb0fdcee8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_3125b111-85cd-4ce3-81d8-addfb0fdcee8" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3125b111-85cd-4ce3-81d8-addfb0fdcee8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_c7809690-b1d5-46a7-bc45-2a818cbe3646" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_3125b111-85cd-4ce3-81d8-addfb0fdcee8" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_c7809690-b1d5-46a7-bc45-2a818cbe3646" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentInFederalHomeLoanBankStockMember_f955eef9-a6af-4e04-91c7-0030151d5bbf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentInFederalHomeLoanBankStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_c7809690-b1d5-46a7-bc45-2a818cbe3646" xlink:to="loc_us-gaap_InvestmentInFederalHomeLoanBankStockMember_f955eef9-a6af-4e04-91c7-0030151d5bbf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesNarrativeDetails" xlink:type="extended" id="i2df7bf1d13f5467aaab21eef18a22a8e_LoansandAllowanceforLoanLossesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableNetReportedAmount_0fb3c2e2-0e48-4630-b4e4-3414ed8143db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableNetReportedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_LoansAndLeasesReceivableNetReportedAmount_0fb3c2e2-0e48-4630-b4e4-3414ed8143db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableGross_0268a1e6-8fb2-44aa-9274-0b1c16170c81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesReceivableGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_NotesReceivableGross_0268a1e6-8fb2-44aa-9274-0b1c16170c81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing_56dd45bc-851e-43b9-9e90-5244221bbed8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing_56dd45bc-851e-43b9-9e90-5244221bbed8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableNonaccrualInterestIncome_960414e4-642e-44d2-8581-63a7e47e54c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableNonaccrualInterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_FinancingReceivableNonaccrualInterestIncome_960414e4-642e-44d2-8581-63a7e47e54c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfBorrowingRelationshipsSubjectToDefermentCARESAct_14d891cc-ca9b-45c7-84eb-9b4cf2a36888" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfBorrowingRelationshipsSubjectToDefermentCARESAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_fsbc_NumberOfBorrowingRelationshipsSubjectToDefermentCARESAct_14d891cc-ca9b-45c7-84eb-9b4cf2a36888" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfLoansSubjectToDefermentCARESAct_fe83b7a3-7062-4d26-b33e-b93dd45daf78" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfLoansSubjectToDefermentCARESAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_fsbc_NumberOfLoansSubjectToDefermentCARESAct_fe83b7a3-7062-4d26-b33e-b93dd45daf78" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_LoansAndLeasesReceivableSubjectToDefermentCARESAct_4a0208b5-1a69-446d-8dde-edf9e0e71b22" xlink:href="fsbc-20220630.xsd#fsbc_LoansAndLeasesReceivableSubjectToDefermentCARESAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_fsbc_LoansAndLeasesReceivableSubjectToDefermentCARESAct_4a0208b5-1a69-446d-8dde-edf9e0e71b22" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1_9a2a5a70-59d3-4c27-a0c6-753b4250552f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1_9a2a5a70-59d3-4c27-a0c6-753b4250552f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged_46b36c30-ea61-43d9-9cb2-194eea77d7f6" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_fsbc_FederalReserveBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged_46b36c30-ea61-43d9-9cb2-194eea77d7f6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitment_d0808725-0a3c-4fac-bf43-6a0d64ca0227" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_OtherCommitment_d0808725-0a3c-4fac-bf43-6a0d64ca0227" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_8520f42a-067a-4a01-81ac-6a3c61326718" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_b0e2661c-9099-4dab-913f-72e6091cf16e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_83c4a4db-7dfd-4a7a-be43-26ad02dc8cc6" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_b0e2661c-9099-4dab-913f-72e6091cf16e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_20e48e95-c217-4e32-bdf7-633cfe3c21e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivables60To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_b0e2661c-9099-4dab-913f-72e6091cf16e" xlink:to="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_20e48e95-c217-4e32-bdf7-633cfe3c21e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9c487823-98d9-46b1-8713-9e0deede86e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9c487823-98d9-46b1-8713-9e0deede86e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_9c487823-98d9-46b1-8713-9e0deede86e6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9c487823-98d9-46b1-8713-9e0deede86e6" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_9c487823-98d9-46b1-8713-9e0deede86e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_287d077a-2c8c-4ad7-91fd-ba79dd1b9016" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9c487823-98d9-46b1-8713-9e0deede86e6" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_287d077a-2c8c-4ad7-91fd-ba79dd1b9016" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfundedLoanCommitmentMember_a442500c-b76e-49ae-aaa1-c8dd87c508d0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnfundedLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_287d077a-2c8c-4ad7-91fd-ba79dd1b9016" xlink:to="loc_us-gaap_UnfundedLoanCommitmentMember_a442500c-b76e-49ae-aaa1-c8dd87c508d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_15ffae88-fc5d-4a84-a186-5bdc711414f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_15ffae88-fc5d-4a84-a186-5bdc711414f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_15ffae88-fc5d-4a84-a186-5bdc711414f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_15ffae88-fc5d-4a84-a186-5bdc711414f9" xlink:to="loc_us-gaap_RelatedPartyDomain_15ffae88-fc5d-4a84-a186-5bdc711414f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_b11054e6-aac4-4a7e-8795-7248219625b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_15ffae88-fc5d-4a84-a186-5bdc711414f9" xlink:to="loc_us-gaap_RelatedPartyDomain_b11054e6-aac4-4a7e-8795-7248219625b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_d959628c-faa3-4d0e-9425-3617c144d656" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_b11054e6-aac4-4a7e-8795-7248219625b5" xlink:to="loc_srt_AffiliatedEntityMember_d959628c-faa3-4d0e-9425-3617c144d656" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveBankBranchAxis_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveBankBranchAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_d0a5b030-e5bc-411b-ad5d-fe2ba29e628c" xlink:to="loc_fsbc_FederalReserveBankBranchAxis_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveBankBranchDomain_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc_default" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveBankBranchDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_fsbc_FederalReserveBankBranchAxis_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc" xlink:to="loc_fsbc_FederalReserveBankBranchDomain_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveBankBranchDomain_91a610e5-7fe9-4e16-a602-0f96f8b58c42" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveBankBranchDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_fsbc_FederalReserveBankBranchAxis_5c6a31a8-f689-4cc0-8d9b-ebf6921d86cc" xlink:to="loc_fsbc_FederalReserveBankBranchDomain_91a610e5-7fe9-4e16-a602-0f96f8b58c42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveBankOfSanFranciscoMember_f69b25b5-60fa-483b-8d62-c22cb191db51" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveBankOfSanFranciscoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_FederalReserveBankBranchDomain_91a610e5-7fe9-4e16-a602-0f96f8b58c42" xlink:to="loc_fsbc_FederalReserveBankOfSanFranciscoMember_f69b25b5-60fa-483b-8d62-c22cb191db51" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesBalanceofEachMajorProductTypeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesBalanceofEachMajorProductTypeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesBalanceofEachMajorProductTypeDetails" xlink:type="extended" id="ifd3d4d35eff94cdd88fd620f9213e453_LoansandAllowanceforLoanLossesBalanceofEachMajorProductTypeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_bd495586-5b9b-4d66-bfaf-4db905bbd082" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableGrossCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_bd495586-5b9b-4d66-bfaf-4db905bbd082" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableDeferredIncome_4139204d-5b63-4672-9563-24f8b3e8ea88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableDeferredIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableDeferredIncome_4139204d-5b63-4672-9563-24f8b3e8ea88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowance_b7b19d9d-9274-4693-bff4-285b97c07edc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableAllowance_b7b19d9d-9274-4693-bff4-285b97c07edc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableNetReportedAmount_df5a4458-1795-4409-a7fe-9329fdd545a1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableNetReportedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableNetReportedAmount_df5a4458-1795-4409-a7fe-9329fdd545a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_0d782888-6d0f-4822-8da7-ded4c834d84b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_72e59fb2-bcdf-42ef-91ea-a229bc5e8cbc" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_0d782888-6d0f-4822-8da7-ded4c834d84b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_053e0c84-61c7-4093-82b3-2425103c0675" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_0d782888-6d0f-4822-8da7-ded4c834d84b" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_053e0c84-61c7-4093-82b3-2425103c0675" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_053e0c84-61c7-4093-82b3-2425103c0675_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_053e0c84-61c7-4093-82b3-2425103c0675" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_053e0c84-61c7-4093-82b3-2425103c0675_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_053e0c84-61c7-4093-82b3-2425103c0675" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_81e1cb3d-38b1-472a-b9a4-b14336a5c54b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_us-gaap_CommercialRealEstateMember_81e1cb3d-38b1-472a-b9a4-b14336a5c54b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_c5ecef9b-7f58-4761-b528-93c59565c783" xlink:href="fsbc-20220630.xsd#fsbc_RealEstateCommercialLandAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_c5ecef9b-7f58-4761-b528-93c59565c783" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialConstructionLoansMember_029777f0-7ec2-408c-98c8-51c3418586c4" xlink:href="fsbc-20220630.xsd#fsbc_CommercialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_fsbc_CommercialConstructionLoansMember_029777f0-7ec2-408c-98c8-51c3418586c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ResidentialConstructionLoansMember_5195f87c-2e91-4018-9303-86d2f8865aa2" xlink:href="fsbc-20220630.xsd#fsbc_ResidentialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_fsbc_ResidentialConstructionLoansMember_5195f87c-2e91-4018-9303-86d2f8865aa2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_bfe3ac0a-79ce-454a-b8c9-393b1bbb180d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_us-gaap_ResidentialRealEstateMember_bfe3ac0a-79ce-454a-b8c9-393b1bbb180d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FarmlandMember_724ba1b9-8ece-4d59-8cf0-1a72b1835c02" xlink:href="fsbc-20220630.xsd#fsbc_FarmlandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_fsbc_FarmlandMember_724ba1b9-8ece-4d59-8cf0-1a72b1835c02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_9f8b4e43-3e19-4dd2-afb7-d3997b5be60e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_us-gaap_SecuredDebtMember_9f8b4e43-3e19-4dd2-afb7-d3997b5be60e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_c2bffa51-9120-44c2-94bc-4a645a422d12" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_us-gaap_UnsecuredDebtMember_c2bffa51-9120-44c2-94bc-4a645a422d12" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialPaycheckProtectionProgramMember_fdbc4f23-a531-4ba9-854e-cd2bb2517943" xlink:href="fsbc-20220630.xsd#fsbc_CommercialPaycheckProtectionProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_fsbc_CommercialPaycheckProtectionProgramMember_fdbc4f23-a531-4ba9-854e-cd2bb2517943" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_6ca46281-7015-418f-8f13-f0a18d2c1831" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_214dd767-fdbe-48e2-b36b-c1c2a919c2c9" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_6ca46281-7015-418f-8f13-f0a18d2c1831" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesCreditQualityIndicatorsRelatedtotheCompanysLoansbyClassDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesCreditQualityIndicatorsRelatedtotheCompanysLoansbyClassDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesCreditQualityIndicatorsRelatedtotheCompanysLoansbyClassDetails" xlink:type="extended" id="i3ef0b009819143a8af38b367acccfe95_LoansandAllowanceforLoanLossesCreditQualityIndicatorsRelatedtotheCompanysLoansbyClassDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_953d02d2-9b4b-4d46-ab39-ad288148e473" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_88bb1e5a-6d12-4fd6-96e5-5e70e7b9f6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableGrossCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_953d02d2-9b4b-4d46-ab39-ad288148e473" xlink:to="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_88bb1e5a-6d12-4fd6-96e5-5e70e7b9f6e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_2ffaf382-c8ef-41f8-a869-cf1565006aac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_953d02d2-9b4b-4d46-ab39-ad288148e473" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_2ffaf382-c8ef-41f8-a869-cf1565006aac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_2ffaf382-c8ef-41f8-a869-cf1565006aac" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_eef6f88e-73a3-4b4e-ae3d-14e5c2ad5062" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_2a568236-750c-434f-8662-f4e4049caf82" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_us-gaap_CommercialRealEstateMember_2a568236-750c-434f-8662-f4e4049caf82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_82e1b00f-cfd3-47de-b5f3-431380f00820" xlink:href="fsbc-20220630.xsd#fsbc_RealEstateCommercialLandAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_82e1b00f-cfd3-47de-b5f3-431380f00820" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialConstructionLoansMember_d983419b-cd5b-4f5f-8b00-75dd8d3d13c2" xlink:href="fsbc-20220630.xsd#fsbc_CommercialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_fsbc_CommercialConstructionLoansMember_d983419b-cd5b-4f5f-8b00-75dd8d3d13c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ResidentialConstructionLoansMember_60035d34-4447-4e4e-b858-cbcaa1cc1821" xlink:href="fsbc-20220630.xsd#fsbc_ResidentialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_fsbc_ResidentialConstructionLoansMember_60035d34-4447-4e4e-b858-cbcaa1cc1821" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_3e1d224f-d221-43c7-af8a-ad5dfe3170d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_us-gaap_ResidentialRealEstateMember_3e1d224f-d221-43c7-af8a-ad5dfe3170d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FarmlandMember_e179991c-d966-41ba-8af9-8dce7693f8ae" xlink:href="fsbc-20220630.xsd#fsbc_FarmlandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_fsbc_FarmlandMember_e179991c-d966-41ba-8af9-8dce7693f8ae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_c53e2b82-aa4f-41fd-a1f0-b2e8a8a3517d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_us-gaap_SecuredDebtMember_c53e2b82-aa4f-41fd-a1f0-b2e8a8a3517d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_a9ae1d8e-b7da-4584-910e-3cf62464fd52" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_us-gaap_UnsecuredDebtMember_a9ae1d8e-b7da-4584-910e-3cf62464fd52" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialPaycheckProtectionProgramMember_ae67ec95-7ad3-432c-aaca-7115d50cba91" xlink:href="fsbc-20220630.xsd#fsbc_CommercialPaycheckProtectionProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_fsbc_CommercialPaycheckProtectionProgramMember_ae67ec95-7ad3-432c-aaca-7115d50cba91" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_0a77d98e-b599-4bbf-a732-cb70c7505e17" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_667b967a-6360-4983-8eed-9ba56f0c5927" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_0a77d98e-b599-4bbf-a732-cb70c7505e17" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentAxis_449a78d6-e7da-4618-ae63-62a711e7fcd2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InternalCreditAssessmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_2ffaf382-c8ef-41f8-a869-cf1565006aac" xlink:to="loc_us-gaap_InternalCreditAssessmentAxis_449a78d6-e7da-4618-ae63-62a711e7fcd2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_449a78d6-e7da-4618-ae63-62a711e7fcd2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_449a78d6-e7da-4618-ae63-62a711e7fcd2" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_449a78d6-e7da-4618-ae63-62a711e7fcd2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_449a78d6-e7da-4618-ae63-62a711e7fcd2" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassMember_b582dc29-03ae-49fe-b025-b6e08e230dca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PassMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:to="loc_us-gaap_PassMember_b582dc29-03ae-49fe-b025-b6e08e230dca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_WatchMember_fa055de7-33f5-43b7-8e91-a94df0688572" xlink:href="fsbc-20220630.xsd#fsbc_WatchMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:to="loc_fsbc_WatchMember_fa055de7-33f5-43b7-8e91-a94df0688572" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubstandardMember_2f4704c9-67e4-4dcb-bf08-33bb7541b406" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubstandardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:to="loc_us-gaap_SubstandardMember_2f4704c9-67e4-4dcb-bf08-33bb7541b406" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DoubtfulMember_31c7e322-244f-41fc-8577-2c86baf82758" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DoubtfulMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_f5f902b5-fc35-493c-b227-2d8747827b61" xlink:to="loc_us-gaap_DoubtfulMember_31c7e322-244f-41fc-8577-2c86baf82758" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesAgeAnalysisofPastDueLoansbyClassDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesAgeAnalysisofPastDueLoansbyClassDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesAgeAnalysisofPastDueLoansbyClassDetails" xlink:type="extended" id="idd95c95dd0184a8798a936566f6cb98a_LoansandAllowanceforLoanLossesAgeAnalysisofPastDueLoansbyClassDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c3e88e7b-d21f-4a78-a3a2-3481001fafeb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_6e36f0d2-d235-407e-9153-015c13afa66b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableGrossCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c3e88e7b-d21f-4a78-a3a2-3481001fafeb" xlink:to="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_6e36f0d2-d235-407e-9153-015c13afa66b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_bc59561d-7308-45b3-afe5-48d431851ea2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c3e88e7b-d21f-4a78-a3a2-3481001fafeb" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_bc59561d-7308-45b3-afe5-48d431851ea2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_4279dd29-5822-456c-8a97-24e13fb5c6cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_bc59561d-7308-45b3-afe5-48d431851ea2" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_4279dd29-5822-456c-8a97-24e13fb5c6cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4279dd29-5822-456c-8a97-24e13fb5c6cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_4279dd29-5822-456c-8a97-24e13fb5c6cb" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4279dd29-5822-456c-8a97-24e13fb5c6cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_4279dd29-5822-456c-8a97-24e13fb5c6cb" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_8a2722ec-5f88-4dfb-b6e1-1e0eeb3478ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_us-gaap_CommercialRealEstateMember_8a2722ec-5f88-4dfb-b6e1-1e0eeb3478ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_4c639046-aa54-4c40-89f4-9692a324889f" xlink:href="fsbc-20220630.xsd#fsbc_RealEstateCommercialLandAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_4c639046-aa54-4c40-89f4-9692a324889f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialConstructionLoansMember_5e50fe39-b446-445f-ae88-e3c45bee10d5" xlink:href="fsbc-20220630.xsd#fsbc_CommercialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_fsbc_CommercialConstructionLoansMember_5e50fe39-b446-445f-ae88-e3c45bee10d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ResidentialConstructionLoansMember_46728fb3-c20e-40ba-8734-42b2254a4e24" xlink:href="fsbc-20220630.xsd#fsbc_ResidentialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_fsbc_ResidentialConstructionLoansMember_46728fb3-c20e-40ba-8734-42b2254a4e24" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_d5e1cd22-9d12-4b11-87a3-0a20b025fe5f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_us-gaap_ResidentialRealEstateMember_d5e1cd22-9d12-4b11-87a3-0a20b025fe5f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FarmlandMember_0e595684-805e-46f6-b804-2f5191861365" xlink:href="fsbc-20220630.xsd#fsbc_FarmlandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_fsbc_FarmlandMember_0e595684-805e-46f6-b804-2f5191861365" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_3a1f1a2b-7ceb-46cb-bee2-c2ed3cca8f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_us-gaap_SecuredDebtMember_3a1f1a2b-7ceb-46cb-bee2-c2ed3cca8f2a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_2bbf6057-8d7e-4e2a-9a88-7572b83a6391" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_us-gaap_UnsecuredDebtMember_2bbf6057-8d7e-4e2a-9a88-7572b83a6391" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialPaycheckProtectionProgramMember_407c6c74-ff01-4ef8-85f0-ef7319df3090" xlink:href="fsbc-20220630.xsd#fsbc_CommercialPaycheckProtectionProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_fsbc_CommercialPaycheckProtectionProgramMember_407c6c74-ff01-4ef8-85f0-ef7319df3090" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_979558ef-8268-46ff-8017-5839a26440c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7267ca41-85f9-4161-9feb-28a3c7bc08fd" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_979558ef-8268-46ff-8017-5839a26440c2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_352d88de-a452-44b2-91eb-10382fa64457" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_bc59561d-7308-45b3-afe5-48d431851ea2" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_352d88de-a452-44b2-91eb-10382fa64457" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_352d88de-a452-44b2-91eb-10382fa64457_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_352d88de-a452-44b2-91eb-10382fa64457" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_352d88de-a452-44b2-91eb-10382fa64457_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_352d88de-a452-44b2-91eb-10382fa64457" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FinancingReceivables30To89DaysPastDueMember_14412c4d-1f30-41c8-bde3-c0a5e08f4767" xlink:href="fsbc-20220630.xsd#fsbc_FinancingReceivables30To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:to="loc_fsbc_FinancingReceivables30To89DaysPastDueMember_14412c4d-1f30-41c8-bde3-c0a5e08f4767" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_add05160-6cf0-466b-aebb-7584b72e9f22" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:to="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_add05160-6cf0-466b-aebb-7584b72e9f22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetPastDueMember_ea80d770-efff-45c2-832a-b345ed5bb2e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialAssetPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:to="loc_us-gaap_FinancialAssetPastDueMember_ea80d770-efff-45c2-832a-b345ed5bb2e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetNotPastDueMember_2caa0bc7-04f4-42c0-8fca-de9ebdac40c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialAssetNotPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_5bd68138-a33a-4060-a67f-a41017211c5a" xlink:to="loc_us-gaap_FinancialAssetNotPastDueMember_2caa0bc7-04f4-42c0-8fca-de9ebdac40c2" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesImpairedLoansDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesImpairedLoansDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesImpairedLoansDetails" xlink:type="extended" id="ib85a5fe7cacd42d0a7402ccb852b36a1_LoansandAllowanceforLoanLossesImpairedLoansDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract_6f9a596a-a1a1-41be-9b22-53a380189e43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract_6f9a596a-a1a1-41be-9b22-53a380189e43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment_9ca8bd00-fcfa-438a-b234-2e6583e0030e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract_6f9a596a-a1a1-41be-9b22-53a380189e43" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment_9ca8bd00-fcfa-438a-b234-2e6583e0030e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment_a1f09330-c836-470c-b31e-5f2e6f8f30fb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract_6f9a596a-a1a1-41be-9b22-53a380189e43" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment_a1f09330-c836-470c-b31e-5f2e6f8f30fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestment_3259e512-c4b8-4687-9cb9-09cc1f8f408c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestmentAbstract_6f9a596a-a1a1-41be-9b22-53a380189e43" xlink:to="loc_us-gaap_ImpairedFinancingReceivableRecordedInvestment_3259e512-c4b8-4687-9cb9-09cc1f8f408c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract_ebf37cc1-7c7e-4153-a9c4-4718f5d585a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract_ebf37cc1-7c7e-4153-a9c4-4718f5d585a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance_a8c57298-ec89-4352-a171-dd40c748db40" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract_ebf37cc1-7c7e-4153-a9c4-4718f5d585a6" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance_a8c57298-ec89-4352-a171-dd40c748db40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance_b3e34eba-9da5-4e97-a0e4-32a5cec15c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract_ebf37cc1-7c7e-4153-a9c4-4718f5d585a6" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance_b3e34eba-9da5-4e97-a0e4-32a5cec15c3f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance_02bc0357-636d-4620-8e8c-39f70ab7907c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalanceAbstract_ebf37cc1-7c7e-4153-a9c4-4718f5d585a6" xlink:to="loc_us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance_02bc0357-636d-4620-8e8c-39f70ab7907c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableRelatedAllowance_7d7d1786-a902-46f7-af4a-9b81d13451cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableRelatedAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ImpairedFinancingReceivableRelatedAllowance_7d7d1786-a902-46f7-af4a-9b81d13451cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract_7f5079d8-2fa2-4d22-8521-1a3498505b95" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract_7f5079d8-2fa2-4d22-8521-1a3498505b95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment_5348b396-7575-41f7-beba-7adce4a0c5cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract_7f5079d8-2fa2-4d22-8521-1a3498505b95" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment_5348b396-7575-41f7-beba-7adce4a0c5cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment_c96c7f81-c205-4820-b242-12cb4d4f8b93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract_7f5079d8-2fa2-4d22-8521-1a3498505b95" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment_c96c7f81-c205-4820-b242-12cb4d4f8b93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment_132c3f01-cfe8-4264-a2b0-8ba6c0ac1e3a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestmentAbstract_7f5079d8-2fa2-4d22-8521-1a3498505b95" xlink:to="loc_us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment_132c3f01-cfe8-4264-a2b0-8ba6c0ac1e3a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract_f94077ca-7f8d-4992-96e4-1484f326d358" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract_f94077ca-7f8d-4992-96e4-1484f326d358" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod_5243f04a-6d88-448d-9092-bc31354f9a79" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract_f94077ca-7f8d-4992-96e4-1484f326d358" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod_5243f04a-6d88-448d-9092-bc31354f9a79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod_f4c286b0-b8fd-4eae-b1e9-454be92ca7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract_f94077ca-7f8d-4992-96e4-1484f326d358" xlink:to="loc_us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod_f4c286b0-b8fd-4eae-b1e9-454be92ca7e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod_8f8af500-19d5-40ad-ae2b-253ec4c7d94c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethodAbstract_f94077ca-7f8d-4992-96e4-1484f326d358" xlink:to="loc_us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod_8f8af500-19d5-40ad-ae2b-253ec4c7d94c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f15ce240-0c6d-4241-9af6-7d2692caf79d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_2b8f1676-5294-4089-9e48-4a325ad11043" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f15ce240-0c6d-4241-9af6-7d2692caf79d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f65ba32c-d21c-4023-a5d1-bfe14a293fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f15ce240-0c6d-4241-9af6-7d2692caf79d" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f65ba32c-d21c-4023-a5d1-bfe14a293fa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_f65ba32c-d21c-4023-a5d1-bfe14a293fa6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f65ba32c-d21c-4023-a5d1-bfe14a293fa6" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_f65ba32c-d21c-4023-a5d1-bfe14a293fa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f65ba32c-d21c-4023-a5d1-bfe14a293fa6" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_9f7f449d-e525-4881-ad08-3933f2012049" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:to="loc_us-gaap_CommercialRealEstateMember_9f7f449d-e525-4881-ad08-3933f2012049" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_d28958a7-fa33-4d77-83d0-107440326574" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:to="loc_us-gaap_ResidentialRealEstateMember_d28958a7-fa33-4d77-83d0-107440326574" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_ef29005f-b50d-41d4-826d-2ecc04db8379" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:to="loc_us-gaap_SecuredDebtMember_ef29005f-b50d-41d4-826d-2ecc04db8379" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ConsumerAndOtherMember_ced2caa1-b2f1-46dd-ab30-de52b2ffa8af" xlink:href="fsbc-20220630.xsd#fsbc_ConsumerAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b1ed9662-a482-44f9-b1ad-afcfb743d70f" xlink:to="loc_fsbc_ConsumerAndOtherMember_ced2caa1-b2f1-46dd-ab30-de52b2ffa8af" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesNonaccrualLoansSegregatedbyClassDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesNonaccrualLoansSegregatedbyClassDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesNonaccrualLoansSegregatedbyClassDetails" xlink:type="extended" id="iddb3581d4c0d476a82ad3cfeba3f9a22_LoansandAllowanceforLoanLossesNonaccrualLoansSegregatedbyClassDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_95365722-28f9-4ca2-9e06-5b68931e577d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus_3c37e32f-8b25-4e62-93e2-ef0c9871ac9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_95365722-28f9-4ca2-9e06-5b68931e577d" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus_3c37e32f-8b25-4e62-93e2-ef0c9871ac9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_c6e9fbee-426f-479c-8f05-8114fa16473c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_95365722-28f9-4ca2-9e06-5b68931e577d" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_c6e9fbee-426f-479c-8f05-8114fa16473c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_0855a7a0-fd7c-44bd-af17-22b52d66325a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_c6e9fbee-426f-479c-8f05-8114fa16473c" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_0855a7a0-fd7c-44bd-af17-22b52d66325a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_0855a7a0-fd7c-44bd-af17-22b52d66325a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_0855a7a0-fd7c-44bd-af17-22b52d66325a" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_0855a7a0-fd7c-44bd-af17-22b52d66325a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b3fecaba-53c4-4d8d-b36f-335a31102351" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_0855a7a0-fd7c-44bd-af17-22b52d66325a" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b3fecaba-53c4-4d8d-b36f-335a31102351" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_1acc2d8e-8000-41ff-a68e-b08042bbc547" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b3fecaba-53c4-4d8d-b36f-335a31102351" xlink:to="loc_us-gaap_CommercialRealEstateMember_1acc2d8e-8000-41ff-a68e-b08042bbc547" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_f5619260-b1b1-4016-abfd-e18650708ef0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b3fecaba-53c4-4d8d-b36f-335a31102351" xlink:to="loc_us-gaap_ResidentialRealEstateMember_f5619260-b1b1-4016-abfd-e18650708ef0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_71883912-f276-4823-8582-b67dad207e10" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b3fecaba-53c4-4d8d-b36f-335a31102351" xlink:to="loc_us-gaap_SecuredDebtMember_71883912-f276-4823-8582-b67dad207e10" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesAllowanceforLoanLossesDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LoansandAllowanceforLoanLossesAllowanceforLoanLossesDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LoansandAllowanceforLoanLossesAllowanceforLoanLossesDetails" xlink:type="extended" id="idee9eb2f40b542ba8e5b12552f349525_LoansandAllowanceforLoanLossesAllowanceforLoanLossesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_77af2648-95b5-4320-8e51-10f847aef6fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_77af2648-95b5-4320-8e51-10f847aef6fd" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowance_75f6b04a-70ca-4b15-a47e-f9dec450f16d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableAllowance_75f6b04a-70ca-4b15-a47e-f9dec450f16d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs_b2a12ffc-1de6-45bc-82d1-30280b373668" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs_b2a12ffc-1de6-45bc-82d1-30280b373668" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery_484446d0-0d3d-4799-8607-1a77054670e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery_484446d0-0d3d-4799-8607-1a77054670e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanAndLeaseLosses_0ac7dd13-05bb-44ba-86c0-8284338876c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProvisionForLoanAndLeaseLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_ProvisionForLoanAndLeaseLosses_0ac7dd13-05bb-44ba-86c0-8284338876c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowance_f0b6f91f-868a-4930-a485-f5cd36aabfe0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowance"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1_05e0dcd5-4497-400c-bfab-c55a5576bf5d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1_05e0dcd5-4497-400c-bfab-c55a5576bf5d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment_db681166-e02f-4f25-aa5a-46abd0699367" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment_db681166-e02f-4f25-aa5a-46abd0699367" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLosses_991aa1a6-93f1-4e9e-893f-b0430db4337f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLosses_991aa1a6-93f1-4e9e-893f-b0430db4337f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract_a4a560b3-4a14-4df6-86df-5ce82ca0230c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract_a4a560b3-4a14-4df6-86df-5ce82ca0230c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment_b20a5374-f8be-49f7-a860-01dc2fe9b1af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract_a4a560b3-4a14-4df6-86df-5ce82ca0230c" xlink:to="loc_us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment_b20a5374-f8be-49f7-a860-01dc2fe9b1af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment_648f598b-616b-4f16-b8c0-46b85788ee9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract_a4a560b3-4a14-4df6-86df-5ce82ca0230c" xlink:to="loc_us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment_648f598b-616b-4f16-b8c0-46b85788ee9a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_9768715f-7401-495e-ba1f-3911ee350308" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableGrossCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_551f3f30-0085-4fa7-a5c7-d0fb86b6fecc" xlink:to="loc_us-gaap_LoansAndLeasesReceivableGrossCarryingAmount_9768715f-7401-495e-ba1f-3911ee350308" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9409a73a-b189-4867-97a0-5370ff47def0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_77af2648-95b5-4320-8e51-10f847aef6fd" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9409a73a-b189-4867-97a0-5370ff47def0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fabb6b01-263c-4e57-926f-d744ad891f91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9409a73a-b189-4867-97a0-5370ff47def0" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fabb6b01-263c-4e57-926f-d744ad891f91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fabb6b01-263c-4e57-926f-d744ad891f91_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fabb6b01-263c-4e57-926f-d744ad891f91" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fabb6b01-263c-4e57-926f-d744ad891f91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fabb6b01-263c-4e57-926f-d744ad891f91" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstateMember_87e671bb-48bb-48c2-b433-22813a704f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_CommercialRealEstateMember_87e671bb-48bb-48c2-b433-22813a704f5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_3d205d59-db90-4daa-996a-cdeb17b8eb92" xlink:href="fsbc-20220630.xsd#fsbc_RealEstateCommercialLandAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_fsbc_RealEstateCommercialLandAndDevelopmentMember_3d205d59-db90-4daa-996a-cdeb17b8eb92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialConstructionLoansMember_e5581001-a1eb-4744-88cb-ea80aa80a620" xlink:href="fsbc-20220630.xsd#fsbc_CommercialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_fsbc_CommercialConstructionLoansMember_e5581001-a1eb-4744-88cb-ea80aa80a620" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ResidentialConstructionLoansMember_29837be5-f6d5-4992-8d21-169ec16cd491" xlink:href="fsbc-20220630.xsd#fsbc_ResidentialConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_fsbc_ResidentialConstructionLoansMember_29837be5-f6d5-4992-8d21-169ec16cd491" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialRealEstateMember_bc7ec912-be41-4f8f-be3a-41ae1678448e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResidentialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_ResidentialRealEstateMember_bc7ec912-be41-4f8f-be3a-41ae1678448e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FarmlandMember_ca80a7fd-b8f9-4deb-bf91-3893d21a304b" xlink:href="fsbc-20220630.xsd#fsbc_FarmlandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_fsbc_FarmlandMember_ca80a7fd-b8f9-4deb-bf91-3893d21a304b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_329b5c27-68d9-40b4-b66c-00af199826f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_SecuredDebtMember_329b5c27-68d9-40b4-b66c-00af199826f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_eadd9320-73a2-4d39-b4b8-fad26ea9371b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_UnsecuredDebtMember_eadd9320-73a2-4d39-b4b8-fad26ea9371b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialPaycheckProtectionProgramMember_ac767c0e-2664-447c-8696-b0936c700b7e" xlink:href="fsbc-20220630.xsd#fsbc_CommercialPaycheckProtectionProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_fsbc_CommercialPaycheckProtectionProgramMember_ac767c0e-2664-447c-8696-b0936c700b7e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_a0d70c0b-7a64-4785-b952-0a110305be3c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_a0d70c0b-7a64-4785-b952-0a110305be3c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnallocatedFinancingReceivablesMember_9cab2abf-3e8b-4a00-bb44-b693c6988a81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnallocatedFinancingReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_4de572cf-e729-4c20-83dc-06d814408496" xlink:to="loc_us-gaap_UnallocatedFinancingReceivablesMember_9cab2abf-3e8b-4a00-bb44-b693c6988a81" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/InterestBearingDepositsCompositionofNetworkDepositsDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#InterestBearingDepositsCompositionofNetworkDepositsDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/InterestBearingDepositsCompositionofNetworkDepositsDetails" xlink:type="extended" id="i195cb140e48342b88ec562b676030a4b_InterestBearingDepositsCompositionofNetworkDepositsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_InterestBearingDepositsLineItems_cac827f9-249d-430d-b604-19113adaa816" xlink:href="fsbc-20220630.xsd#fsbc_InterestBearingDepositsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NetworkDeposits_86b78570-9bdb-4a3e-b709-7d4239d9e01e" xlink:href="fsbc-20220630.xsd#fsbc_NetworkDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_fsbc_InterestBearingDepositsLineItems_cac827f9-249d-430d-b604-19113adaa816" xlink:to="loc_fsbc_NetworkDeposits_86b78570-9bdb-4a3e-b709-7d4239d9e01e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_InterestBearingDepositsTable_d4af9980-bb8b-4188-8045-8c42d662e2fd" xlink:href="fsbc-20220630.xsd#fsbc_InterestBearingDepositsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_fsbc_InterestBearingDepositsLineItems_cac827f9-249d-430d-b604-19113adaa816" xlink:to="loc_fsbc_InterestBearingDepositsTable_d4af9980-bb8b-4188-8045-8c42d662e2fd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_8e4a924e-4211-441d-a991-9fcb3f3b0ece" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_fsbc_InterestBearingDepositsTable_d4af9980-bb8b-4188-8045-8c42d662e2fd" xlink:to="loc_srt_ProductOrServiceAxis_8e4a924e-4211-441d-a991-9fcb3f3b0ece" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_8e4a924e-4211-441d-a991-9fcb3f3b0ece_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_8e4a924e-4211-441d-a991-9fcb3f3b0ece" xlink:to="loc_srt_ProductsAndServicesDomain_8e4a924e-4211-441d-a991-9fcb3f3b0ece_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_93d87283-daee-40c1-98fc-c06f131459a8" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_8e4a924e-4211-441d-a991-9fcb3f3b0ece" xlink:to="loc_srt_ProductsAndServicesDomain_93d87283-daee-40c1-98fc-c06f131459a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CDARSMember_a059a094-436f-49ea-8317-25de1562ec36" xlink:href="fsbc-20220630.xsd#fsbc_CDARSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_93d87283-daee-40c1-98fc-c06f131459a8" xlink:to="loc_fsbc_CDARSMember_a059a094-436f-49ea-8317-25de1562ec36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ICSMember_e8e923c1-46d7-46da-ab79-4447942e28f0" xlink:href="fsbc-20220630.xsd#fsbc_ICSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_93d87283-daee-40c1-98fc-c06f131459a8" xlink:to="loc_fsbc_ICSMember_e8e923c1-46d7-46da-ab79-4447942e28f0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LeasesNarrativeDetails" xlink:type="extended" id="i21ea83bcf1884bf491542d5659882d8a_LeasesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_46a578fb-a2e5-471d-ad49-0a02ddc83dae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_46a578fb-a2e5-471d-ad49-0a02ddc83dae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_c4b355d5-2362-4651-bd93-0f2c3b86097b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:to="loc_us-gaap_OperatingLeaseExpense_c4b355d5-2362-4651-bd93-0f2c3b86097b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseAndRentalExpense_ea4772dd-a9ce-467a-ae09-972359cbfb61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseAndRentalExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:to="loc_us-gaap_LeaseAndRentalExpense_ea4772dd-a9ce-467a-ae09-972359cbfb61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncome_e6f68849-ac09-47c0-8203-c3ccf59fbbe5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncome_e6f68849-ac09-47c0-8203-c3ccf59fbbe5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_7574a411-818c-47b2-a779-89659cecd551" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_c01a83ec-f90b-4fb5-9bfe-ba3cd095036b" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_7574a411-818c-47b2-a779-89659cecd551" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_0d80b010-301d-4574-a06f-134da1b006d4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_7574a411-818c-47b2-a779-89659cecd551" xlink:to="loc_srt_RangeAxis_0d80b010-301d-4574-a06f-134da1b006d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0d80b010-301d-4574-a06f-134da1b006d4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_0d80b010-301d-4574-a06f-134da1b006d4" xlink:to="loc_srt_RangeMember_0d80b010-301d-4574-a06f-134da1b006d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6200a6e9-f244-4a00-8387-241d86cf98a0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_0d80b010-301d-4574-a06f-134da1b006d4" xlink:to="loc_srt_RangeMember_6200a6e9-f244-4a00-8387-241d86cf98a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_966b1bf1-9f07-44b1-b882-2b228986d3ae" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6200a6e9-f244-4a00-8387-241d86cf98a0" xlink:to="loc_srt_MinimumMember_966b1bf1-9f07-44b1-b882-2b228986d3ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e8b5c511-2b06-4b78-8dc8-f4602ed64eda" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6200a6e9-f244-4a00-8387-241d86cf98a0" xlink:to="loc_srt_MaximumMember_e8b5c511-2b06-4b78-8dc8-f4602ed64eda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_efdbf3cd-e41d-4e2e-a24a-16142f88c808" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_7574a411-818c-47b2-a779-89659cecd551" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_efdbf3cd-e41d-4e2e-a24a-16142f88c808" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_efdbf3cd-e41d-4e2e-a24a-16142f88c808_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_efdbf3cd-e41d-4e2e-a24a-16142f88c808" xlink:to="loc_us-gaap_TypeOfAdoptionMember_efdbf3cd-e41d-4e2e-a24a-16142f88c808_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_0104d0f8-7ff1-459b-81c5-11b9fe876a6e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_efdbf3cd-e41d-4e2e-a24a-16142f88c808" xlink:to="loc_us-gaap_TypeOfAdoptionMember_0104d0f8-7ff1-459b-81c5-11b9fe876a6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_1ee65ab0-44ab-4dba-b66b-8c3fb1cd4ec5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_0104d0f8-7ff1-459b-81c5-11b9fe876a6e" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_1ee65ab0-44ab-4dba-b66b-8c3fb1cd4ec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_7574a411-818c-47b2-a779-89659cecd551" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b" xlink:to="loc_us-gaap_RelatedPartyDomain_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_a2afcf17-65d2-4761-aba7-8bae29109f19" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8d4e7354-67b8-4d7e-84ba-b6ee05ad3b9b" xlink:to="loc_us-gaap_RelatedPartyDomain_a2afcf17-65d2-4761-aba7-8bae29109f19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_4aa34423-7053-4f63-9b63-4c2ce929d3a8" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_a2afcf17-65d2-4761-aba7-8bae29109f19" xlink:to="loc_srt_AffiliatedEntityMember_4aa34423-7053-4f63-9b63-4c2ce929d3a8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/LongTermDebtandOtherBorrowingsDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#LongTermDebtandOtherBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/LongTermDebtandOtherBorrowingsDetails" xlink:type="extended" id="i5f3b241c5bef421da62b68789576e6f0_LongTermDebtandOtherBorrowingsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_f35e7c46-62af-4721-ae58-ca5be4e40475" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubordinatedDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_SubordinatedDebt_f35e7c46-62af-4721-ae58-ca5be4e40475" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfBoardDirectors_05b1b6fa-0c60-46b5-ac72-5ef4937c3ba1" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfBoardDirectors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_fsbc_NumberOfBoardDirectors_05b1b6fa-0c60-46b5-ac72-5ef4937c3ba1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedBorrowingInterestRate_e868eee0-5e07-462e-8b69-37d1f771dc8b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubordinatedBorrowingInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_SubordinatedBorrowingInterestRate_e868eee0-5e07-462e-8b69-37d1f771dc8b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_cd2e8df5-beb1-48ae-9867-ece55f10daab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_cd2e8df5-beb1-48ae-9867-ece55f10daab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_DebtInstrumentFloatingInterestRate_997af62d-09a2-455a-83fa-3eba9393d91a" xlink:href="fsbc-20220630.xsd#fsbc_DebtInstrumentFloatingInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_fsbc_DebtInstrumentFloatingInterestRate_997af62d-09a2-455a-83fa-3eba9393d91a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_56a39bd3-e70f-4a67-a875-52cc383a7493" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_56a39bd3-e70f-4a67-a875-52cc383a7493" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfShareholders_33cee5ed-c234-44f4-a23c-30326c8dbecd" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_fsbc_NumberOfShareholders_33cee5ed-c234-44f4-a23c-30326c8dbecd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_b786dfc6-7398-4c1e-a477-17d3d36a18d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_b786dfc6-7398-4c1e-a477-17d3d36a18d8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedAmortizationDeferredFinanceCosts_b8a9d2f4-8c70-420b-b43d-3ccf034d4238" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedAmortizationDeferredFinanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_AccumulatedAmortizationDeferredFinanceCosts_b8a9d2f4-8c70-420b-b43d-3ccf034d4238" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_26fbcbd2-aa20-4f27-869e-c072cfced485" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_26fbcbd2-aa20-4f27-869e-c072cfced485" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_a9b19ee0-4fc3-4492-b87e-fe19972521ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LineOfCredit_a9b19ee0-4fc3-4492-b87e-fe19972521ce" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_d2a1cd46-b289-48e4-ad3c-7fb07b04ba76" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_d2a1cd46-b289-48e4-ad3c-7fb07b04ba76" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_fdd1deeb-e931-4088-bd56-dbcb3be5110b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_fdd1deeb-e931-4088-bd56-dbcb3be5110b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfUnsecuredFederalFunds_a52a1445-989f-432b-bf83-becc74c99581" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfUnsecuredFederalFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_fsbc_NumberOfUnsecuredFederalFunds_a52a1445-989f-432b-bf83-becc74c99581" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_NumberOfCorrespondentBanks_b21b6507-5d69-4c66-8313-c9b702622e8c" xlink:href="fsbc-20220630.xsd#fsbc_NumberOfCorrespondentBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_fsbc_NumberOfCorrespondentBanks_b21b6507-5d69-4c66-8313-c9b702622e8c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet_8ef25d91-33b6-4e7b-949d-3597d9472e59" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet_8ef25d91-33b6-4e7b-949d-3597d9472e59" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding_1fb423c3-41c1-4f83-9ce5-6e11b5879803" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding_1fb423c3-41c1-4f83-9ce5-6e11b5879803" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc900b86-60fa-4910-9f86-dad3f7cd90a0" xlink:to="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_775d1bff-363a-4ddd-bb55-00e45fc3ae8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_775d1bff-363a-4ddd-bb55-00e45fc3ae8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_775d1bff-363a-4ddd-bb55-00e45fc3ae8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_775d1bff-363a-4ddd-bb55-00e45fc3ae8d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_775d1bff-363a-4ddd-bb55-00e45fc3ae8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3e7bbfc9-7143-470a-b301-4d056c7ae3d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_775d1bff-363a-4ddd-bb55-00e45fc3ae8d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3e7bbfc9-7143-470a-b301-4d056c7ae3d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebtMember_b5c54f17-e820-4bc9-a2ea-3092a36f72b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubordinatedDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3e7bbfc9-7143-470a-b301-4d056c7ae3d5" xlink:to="loc_us-gaap_SubordinatedDebtMember_b5c54f17-e820-4bc9-a2ea-3092a36f72b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_4145c0b6-aac1-4d67-8bc2-19bd5f651a46" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3e7bbfc9-7143-470a-b301-4d056c7ae3d5" xlink:to="loc_us-gaap_LetterOfCreditMember_4145c0b6-aac1-4d67-8bc2-19bd5f651a46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_6e70c60b-51fe-444a-a6fa-41ac077f596e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3e7bbfc9-7143-470a-b301-4d056c7ae3d5" xlink:to="loc_us-gaap_LineOfCreditMember_6e70c60b-51fe-444a-a6fa-41ac077f596e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_a47b1816-dde4-4081-9f2a-e80af55b9904" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_a47b1816-dde4-4081-9f2a-e80af55b9904" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_a47b1816-dde4-4081-9f2a-e80af55b9904_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_a47b1816-dde4-4081-9f2a-e80af55b9904" xlink:to="loc_us-gaap_RelatedPartyDomain_a47b1816-dde4-4081-9f2a-e80af55b9904_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_63647782-e005-4925-8b08-bc30ac2ea59f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_a47b1816-dde4-4081-9f2a-e80af55b9904" xlink:to="loc_us-gaap_RelatedPartyDomain_63647782-e005-4925-8b08-bc30ac2ea59f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember_3339a22f-2243-4799-a59a-48773fe3ef28" xlink:href="fsbc-20220630.xsd#fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_63647782-e005-4925-8b08-bc30ac2ea59f" xlink:to="loc_fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember_3339a22f-2243-4799-a59a-48773fe3ef28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_0eb568a0-e52e-482b-9d6f-9decd94b942e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:to="loc_us-gaap_DebtInstrumentAxis_0eb568a0-e52e-482b-9d6f-9decd94b942e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_0eb568a0-e52e-482b-9d6f-9decd94b942e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_0eb568a0-e52e-482b-9d6f-9decd94b942e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_0eb568a0-e52e-482b-9d6f-9decd94b942e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_0eb568a0-e52e-482b-9d6f-9decd94b942e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FixedToFloatingRateSubordinatedNotesIssuedNov2019Member_056b68f3-d99f-4120-9547-7a7db025661f" xlink:href="fsbc-20220630.xsd#fsbc_FixedToFloatingRateSubordinatedNotesIssuedNov2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_FixedToFloatingRateSubordinatedNotesIssuedNov2019Member_056b68f3-d99f-4120-9547-7a7db025661f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FixedToFloatingRateSubordinatedNotesIssuedSep2017Member_4f356677-5e73-4006-b537-1e66fa6c36d3" xlink:href="fsbc-20220630.xsd#fsbc_FixedToFloatingRateSubordinatedNotesIssuedSep2017Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_FixedToFloatingRateSubordinatedNotesIssuedSep2017Member_4f356677-5e73-4006-b537-1e66fa6c36d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember_f4268621-2dad-4c9a-bee2-6e7ffe6131e4" xlink:href="fsbc-20220630.xsd#fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_EntityControlledByMemberOfBoardOfDirectorsAndThreeShareholdersMember_f4268621-2dad-4c9a-bee2-6e7ffe6131e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_SubordinatedNotesMaturityDateOfSeptember152027Member_04398123-27cc-4084-9bd3-14b7edfdf453" xlink:href="fsbc-20220630.xsd#fsbc_SubordinatedNotesMaturityDateOfSeptember152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_SubordinatedNotesMaturityDateOfSeptember152027Member_04398123-27cc-4084-9bd3-14b7edfdf453" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_LettersOfCreditPledgedAsSecurityForStateOfCaliforniaDepositsMember_88b6e90a-9851-4a62-944c-4c8acd87f881" xlink:href="fsbc-20220630.xsd#fsbc_LettersOfCreditPledgedAsSecurityForStateOfCaliforniaDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_LettersOfCreditPledgedAsSecurityForStateOfCaliforniaDepositsMember_88b6e90a-9851-4a62-944c-4c8acd87f881" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_SecureLocalAgencyDepositMember_233ba964-b20b-4e25-a27a-81f698ab8064" xlink:href="fsbc-20220630.xsd#fsbc_SecureLocalAgencyDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_SecureLocalAgencyDepositMember_233ba964-b20b-4e25-a27a-81f698ab8064" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FederalReserveDiscountWindowMember_162359de-f72e-45e1-baa4-56cbf3c9c48c" xlink:href="fsbc-20220630.xsd#fsbc_FederalReserveDiscountWindowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_FederalReserveDiscountWindowMember_162359de-f72e-45e1-baa4-56cbf3c9c48c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_UnsecuredFederalFundsLineOfCreditMember_97e06a43-3cc8-4f54-b46a-778c6da9dc56" xlink:href="fsbc-20220630.xsd#fsbc_UnsecuredFederalFundsLineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_UnsecuredFederalFundsLineOfCreditMember_97e06a43-3cc8-4f54-b46a-778c6da9dc56" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_FHLBAgreementMember_7a2a50c0-22e8-482f-9264-8fc441ad7af2" xlink:href="fsbc-20220630.xsd#fsbc_FHLBAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5e21f32e-673f-4230-971e-bb056174f502" xlink:to="loc_fsbc_FHLBAgreementMember_7a2a50c0-22e8-482f-9264-8fc441ad7af2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_974816b6-0c5f-471d-baaf-e167a630b2c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5c08d540-33ec-479b-a8cd-7884dc8e9811" xlink:to="loc_us-gaap_VariableRateAxis_974816b6-0c5f-471d-baaf-e167a630b2c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_974816b6-0c5f-471d-baaf-e167a630b2c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_974816b6-0c5f-471d-baaf-e167a630b2c7" xlink:to="loc_us-gaap_VariableRateDomain_974816b6-0c5f-471d-baaf-e167a630b2c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_221bba71-45a6-417b-b0f3-058e21b4eda4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_974816b6-0c5f-471d-baaf-e167a630b2c7" xlink:to="loc_us-gaap_VariableRateDomain_221bba71-45a6-417b-b0f3-058e21b4eda4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_c12ba4f6-366d-4aa8-9020-736846088aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_221bba71-45a6-417b-b0f3-058e21b4eda4" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_c12ba4f6-366d-4aa8-9020-736846088aa7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/ShareholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#ShareholdersEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/ShareholdersEquityNarrativeDetails" xlink:type="extended" id="i986c5a568fd6403dafad9cc624c230f8_ShareholdersEquityNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_519c250d-b458-486a-91d9-de04d465ce71" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_519c250d-b458-486a-91d9-de04d465ce71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_b4a3e930-4a5b-4125-ad9d-90188399d1b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_b4a3e930-4a5b-4125-ad9d-90188399d1b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fb0e5c7a-1a57-4ad8-a3ef-2d0ffb242b61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fb0e5c7a-1a57-4ad8-a3ef-2d0ffb242b61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_8914c396-0403-423d-9894-9dce9c41ecb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_ShareBasedCompensation_8914c396-0403-423d-9894-9dce9c41ecb3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_UnvestedRestrictedShares_6e136ecc-ae4c-46ac-8094-38bcede8ea0c" xlink:href="fsbc-20220630.xsd#fsbc_UnvestedRestrictedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_fsbc_UnvestedRestrictedShares_6e136ecc-ae4c-46ac-8094-38bcede8ea0c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_b436056b-af90-4e79-9ee8-ab33b9ba2680" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_b436056b-af90-4e79-9ee8-ab33b9ba2680" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_57aaa89d-e7cc-4267-a784-6d0c381c5a5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_216308c6-6208-4391-9ef1-ec6dfdc8d60b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_57aaa89d-e7cc-4267-a784-6d0c381c5a5b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_cd9eafa8-3ee8-4320-81e2-bc5e3853d793" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_57aaa89d-e7cc-4267-a784-6d0c381c5a5b" xlink:to="loc_us-gaap_GranteeStatusAxis_cd9eafa8-3ee8-4320-81e2-bc5e3853d793" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_cd9eafa8-3ee8-4320-81e2-bc5e3853d793_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_cd9eafa8-3ee8-4320-81e2-bc5e3853d793" xlink:to="loc_us-gaap_GranteeStatusDomain_cd9eafa8-3ee8-4320-81e2-bc5e3853d793_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_17e6570b-96a0-4376-a0da-988c948db272" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_cd9eafa8-3ee8-4320-81e2-bc5e3853d793" xlink:to="loc_us-gaap_GranteeStatusDomain_17e6570b-96a0-4376-a0da-988c948db272" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_5d3c3a96-f275-4382-8054-d8d0233833a0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedPaymentArrangementEmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_17e6570b-96a0-4376-a0da-988c948db272" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_5d3c3a96-f275-4382-8054-d8d0233833a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_ShareBasedPaymentArrangementExecutivesAndDirectorsMember_f95795a5-a23e-4428-9184-5187c82458e9" xlink:href="fsbc-20220630.xsd#fsbc_ShareBasedPaymentArrangementExecutivesAndDirectorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_17e6570b-96a0-4376-a0da-988c948db272" xlink:to="loc_fsbc_ShareBasedPaymentArrangementExecutivesAndDirectorsMember_f95795a5-a23e-4428-9184-5187c82458e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_797f8d68-72a1-4402-8754-bbcbaf326512" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_57aaa89d-e7cc-4267-a784-6d0c381c5a5b" xlink:to="loc_srt_RangeAxis_797f8d68-72a1-4402-8754-bbcbaf326512" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_797f8d68-72a1-4402-8754-bbcbaf326512_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_797f8d68-72a1-4402-8754-bbcbaf326512" xlink:to="loc_srt_RangeMember_797f8d68-72a1-4402-8754-bbcbaf326512_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c60c3c5a-4e76-4355-b161-a6b1748184b6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_797f8d68-72a1-4402-8754-bbcbaf326512" xlink:to="loc_srt_RangeMember_c60c3c5a-4e76-4355-b161-a6b1748184b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ee817d76-8c9b-4ab4-9e32-043c5b8ce1ba" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c60c3c5a-4e76-4355-b161-a6b1748184b6" xlink:to="loc_srt_MinimumMember_ee817d76-8c9b-4ab4-9e32-043c5b8ce1ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_2901f3fa-01f7-4659-aa13-0e4789b6535a" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_c60c3c5a-4e76-4355-b161-a6b1748184b6" xlink:to="loc_srt_MaximumMember_2901f3fa-01f7-4659-aa13-0e4789b6535a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_57aaa89d-e7cc-4267-a784-6d0c381c5a5b" xlink:to="loc_srt_TitleOfIndividualAxis_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6deb3e73-8805-49d9-b6cb-fa148f4e6d13" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_b4fc831c-9bf7-4820-8e2e-0e3a631bcc8c" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6deb3e73-8805-49d9-b6cb-fa148f4e6d13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficerMember_7c2b2c07-f2bd-4fb2-a0b8-92906b1197e1" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6deb3e73-8805-49d9-b6cb-fa148f4e6d13" xlink:to="loc_srt_OfficerMember_7c2b2c07-f2bd-4fb2-a0b8-92906b1197e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ExecutiveOfficerMember_6a108025-7e56-4008-baa1-87dff320d667" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_6deb3e73-8805-49d9-b6cb-fa148f4e6d13" xlink:to="loc_srt_ExecutiveOfficerMember_6a108025-7e56-4008-baa1-87dff320d667" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/ShareholdersEquitySummaryofUnvestedSharesActivityDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#ShareholdersEquitySummaryofUnvestedSharesActivityDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/ShareholdersEquitySummaryofUnvestedSharesActivityDetails" xlink:type="extended" id="i7f75937a307d4a5c9a57b691b82d9b37_ShareholdersEquitySummaryofUnvestedSharesActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14481b53-18d7-4c3c-bac2-50306c8e798d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14481b53-18d7-4c3c-bac2-50306c8e798d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2bf1d987-9361-4e2f-ad4d-5a61e9c68b92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2bf1d987-9361-4e2f-ad4d-5a61e9c68b92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_53951ad9-d463-4e06-8bca-4daa1c82cb3d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_53951ad9-d463-4e06-8bca-4daa1c82cb3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3a0ab519-4d48-45bf-b522-6c3ab2e14756" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3a0ab519-4d48-45bf-b522-6c3ab2e14756" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c392f0aa-971a-44e3-ade7-64377d09313f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3d19419-d70a-432e-a772-c37ff172395a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c392f0aa-971a-44e3-ade7-64377d09313f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_06b8ec62-0b4d-41bf-ad6f-c008c049f72f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14481b53-18d7-4c3c-bac2-50306c8e798d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_09af49f0-b603-43ae-bf46-161967928857" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_09af49f0-b603-43ae-bf46-161967928857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_df2d5b28-5cf9-40f2-bd57-b5d575afac99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_df2d5b28-5cf9-40f2-bd57-b5d575afac99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a51070c6-7223-4096-bc47-d4a3b9fab065" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a51070c6-7223-4096-bc47-d4a3b9fab065" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2f6aa2d8-92c4-430b-933a-c474d7ef133e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fb46f0d1-d75f-4047-a3e2-b095cd2f9c4f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2f6aa2d8-92c4-430b-933a-c474d7ef133e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_75696359-511c-4ad7-a596-6a08410e79c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_aed89d03-c894-4e8e-96fa-37bd28b8cfa5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14481b53-18d7-4c3c-bac2-50306c8e798d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_aed89d03-c894-4e8e-96fa-37bd28b8cfa5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_15a15d29-bdee-41d3-a57c-49be04575eab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_aed89d03-c894-4e8e-96fa-37bd28b8cfa5" xlink:to="loc_us-gaap_AwardTypeAxis_15a15d29-bdee-41d3-a57c-49be04575eab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_15a15d29-bdee-41d3-a57c-49be04575eab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_15a15d29-bdee-41d3-a57c-49be04575eab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_15a15d29-bdee-41d3-a57c-49be04575eab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_92d7e6a0-e176-4dae-ab39-c751c2068bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_15a15d29-bdee-41d3-a57c-49be04575eab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_92d7e6a0-e176-4dae-ab39-c751c2068bf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_97640562-9e4e-45c5-adf5-4509ee54a8f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_92d7e6a0-e176-4dae-ab39-c751c2068bf4" xlink:to="loc_us-gaap_RestrictedStockMember_97640562-9e4e-45c5-adf5-4509ee54a8f4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/CommitmentsandContingenciesUnfundedLoanCommitmentsandStandbyLettersofCreditDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#CommitmentsandContingenciesUnfundedLoanCommitmentsandStandbyLettersofCreditDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/CommitmentsandContingenciesUnfundedLoanCommitmentsandStandbyLettersofCreditDetails" xlink:type="extended" id="i3badbf354f40478c98377fe6d7a333e3_CommitmentsandContingenciesUnfundedLoanCommitmentsandStandbyLettersofCreditDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_280ff25f-2cf1-4e7e-9823-06ab737f26dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitment_2f8b02b3-048f-419e-ab7e-054edd0e1f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_280ff25f-2cf1-4e7e-9823-06ab737f26dc" xlink:to="loc_us-gaap_OtherCommitment_2f8b02b3-048f-419e-ab7e-054edd0e1f2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_bb998994-cd7a-4880-9a1b-4fe35f613d83" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_280ff25f-2cf1-4e7e-9823-06ab737f26dc" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_bb998994-cd7a-4880-9a1b-4fe35f613d83" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_bb998994-cd7a-4880-9a1b-4fe35f613d83" xlink:to="loc_us-gaap_OtherCommitmentsAxis_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848" xlink:to="loc_us-gaap_OtherCommitmentsDomain_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_5eeb20dc-9e4e-4b27-8669-5e4fd7ccb848" xlink:to="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_CommercialLinesOfCreditMember_6448018d-4912-4787-8e5b-ec4faecb44bf" xlink:href="fsbc-20220630.xsd#fsbc_CommercialLinesOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_CommercialLinesOfCreditMember_6448018d-4912-4787-8e5b-ec4faecb44bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_UndisbursedConstructionLoansMember_1e195e0e-5b6e-485a-96ef-490f001179be" xlink:href="fsbc-20220630.xsd#fsbc_UndisbursedConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_UndisbursedConstructionLoansMember_1e195e0e-5b6e-485a-96ef-490f001179be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_UndisbursedCommercialRealEstateLoansMember_fd724ead-e0a1-4b89-9d81-6821d99f2c68" xlink:href="fsbc-20220630.xsd#fsbc_UndisbursedCommercialRealEstateLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_UndisbursedCommercialRealEstateLoansMember_fd724ead-e0a1-4b89-9d81-6821d99f2c68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_AgriculturalLinesOfCreditMember_9d0eeb45-9b43-4cc8-93c5-c1fd667850c0" xlink:href="fsbc-20220630.xsd#fsbc_AgriculturalLinesOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_AgriculturalLinesOfCreditMember_9d0eeb45-9b43-4cc8-93c5-c1fd667850c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_UndisbursedAgriculturalRealEstateLoansMember_b6bc4e6e-b818-434d-83ae-b6e74ec858a4" xlink:href="fsbc-20220630.xsd#fsbc_UndisbursedAgriculturalRealEstateLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_UndisbursedAgriculturalRealEstateLoansMember_b6bc4e6e-b818-434d-83ae-b6e74ec858a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_OtherCommitmentsMember_b756ffc9-b61f-4f47-b86c-afa69991ea74" xlink:href="fsbc-20220630.xsd#fsbc_OtherCommitmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_713b7352-4202-4c2d-83e9-a42fe2019a87" xlink:to="loc_fsbc_OtherCommitmentsMember_b756ffc9-b61f-4f47-b86c-afa69991ea74" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="fsbc-20220630.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended" id="i15a74ca66ef840a3aab8ce3fa7a7cc9c_CommitmentsandContingenciesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowance_3827787f-646c-4512-b66a-087367c85b25" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_us-gaap_LoansAndLeasesReceivableAllowance_3827787f-646c-4512-b66a-087367c85b25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_RealEstateRelatedLoansPercentage_a7e035f8-c55d-4366-962d-e1c6dcb4886e" xlink:href="fsbc-20220630.xsd#fsbc_RealEstateRelatedLoansPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_RealEstateRelatedLoansPercentage_a7e035f8-c55d-4366-962d-e1c6dcb4886e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_Deposits5MillionOrMoreNumberOfDepositRelationships_034bcf70-fc35-4e13-a113-a11633c9beca" xlink:href="fsbc-20220630.xsd#fsbc_Deposits5MillionOrMoreNumberOfDepositRelationships"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_Deposits5MillionOrMoreNumberOfDepositRelationships_034bcf70-fc35-4e13-a113-a11633c9beca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_Deposits5MillionOrMorePerDeposit_560a8f24-6337-4c5b-a91d-439ea81d3c7a" xlink:href="fsbc-20220630.xsd#fsbc_Deposits5MillionOrMorePerDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_Deposits5MillionOrMorePerDeposit_560a8f24-6337-4c5b-a91d-439ea81d3c7a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_Deposits5MillionOrMoreAmount_6213848b-d3e5-4c36-9e2a-258653dbad70" xlink:href="fsbc-20220630.xsd#fsbc_Deposits5MillionOrMoreAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_Deposits5MillionOrMoreAmount_6213848b-d3e5-4c36-9e2a-258653dbad70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_PercentageOfDepositsOver5MillionToDeposits_8cb9f4ef-160f-4d1a-8bf2-522156ba5981" xlink:href="fsbc-20220630.xsd#fsbc_PercentageOfDepositsOver5MillionToDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_PercentageOfDepositsOver5MillionToDeposits_8cb9f4ef-160f-4d1a-8bf2-522156ba5981" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_LargestSingleDeposit_1bc196b6-2f30-4722-98e8-a665bd4ac590" xlink:href="fsbc-20220630.xsd#fsbc_LargestSingleDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_LargestSingleDeposit_1bc196b6-2f30-4722-98e8-a665bd4ac590" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsbc_PercentageOfLargestSingleDepositToDeposits_ed9918cf-3098-4daa-bb30-6a54419703a3" xlink:href="fsbc-20220630.xsd#fsbc_PercentageOfLargestSingleDepositToDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_fsbc_PercentageOfLargestSingleDepositToDeposits_ed9918cf-3098-4daa-bb30-6a54419703a3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashUninsuredAmount_498e6fa9-b481-470a-abe1-158243b7fb53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashUninsuredAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_us-gaap_CashUninsuredAmount_498e6fa9-b481-470a-abe1-158243b7fb53" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_12bcfb78-d6ff-4785-b3b9-ab9d941b7e6c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7b52ed69-ada7-49db-af54-5ceae288e2c3" xlink:to="loc_us-gaap_OtherCommitmentsTable_12bcfb78-d6ff-4785-b3b9-ab9d941b7e6c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fc132e43-4ce8-4959-9fb9-b506ad54c0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_12bcfb78-d6ff-4785-b3b9-ab9d941b7e6c" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fc132e43-4ce8-4959-9fb9-b506ad54c0c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fc132e43-4ce8-4959-9fb9-b506ad54c0c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fc132e43-4ce8-4959-9fb9-b506ad54c0c3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fc132e43-4ce8-4959-9fb9-b506ad54c0c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_950c29e4-1d4e-4a60-9ddb-954daa3b79c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_fc132e43-4ce8-4959-9fb9-b506ad54c0c3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_950c29e4-1d4e-4a60-9ddb-954daa3b79c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfundedLoanCommitmentMember_3cc2d583-b3b6-44c4-ab0f-3dc2e3aa8e4a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnfundedLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_950c29e4-1d4e-4a60-9ddb-954daa3b79c2" xlink:to="loc_us-gaap_UnfundedLoanCommitmentMember_3cc2d583-b3b6-44c4-ab0f-3dc2e3aa8e4a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fivestarbank.com/role/SubsequentEventsDetailsNarrative" xlink:type="simple" xlink:href="fsbc-20220630.xsd#SubsequentEventsDetailsNarrative"/>
  <link:definitionLink xlink:role="http://fivestarbank.com/role/SubsequentEventsDetailsNarrative" xlink:type="extended" id="i8c2aab9d5345490eb87f0c790448edb3_SubsequentEventsDetailsNarrative">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_df799041-03dc-42f1-b500-7a53b6c7dbd2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_111f7dee-148a-4819-a7d6-c445ff3abf76" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_df799041-03dc-42f1-b500-7a53b6c7dbd2" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_111f7dee-148a-4819-a7d6-c445ff3abf76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_38937d1d-745a-469f-9049-0a75c256c44c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_df799041-03dc-42f1-b500-7a53b6c7dbd2" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_38937d1d-745a-469f-9049-0a75c256c44c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_d03c3981-ab82-41f9-9e85-5f92a7ee1ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_df799041-03dc-42f1-b500-7a53b6c7dbd2" xlink:to="loc_us-gaap_SubsequentEventTable_d03c3981-ab82-41f9-9e85-5f92a7ee1ebc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_94b43b91-3eea-47c3-878a-45aad4c419c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_d03c3981-ab82-41f9-9e85-5f92a7ee1ebc" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_94b43b91-3eea-47c3-878a-45aad4c419c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_94b43b91-3eea-47c3-878a-45aad4c419c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_94b43b91-3eea-47c3-878a-45aad4c419c7" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_94b43b91-3eea-47c3-878a-45aad4c419c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3bce8268-aff6-4983-b41d-9dd0dca3f380" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_94b43b91-3eea-47c3-878a-45aad4c419c7" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3bce8268-aff6-4983-b41d-9dd0dca3f380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_a2b2f9d9-3195-4a62-bfaf-f2e1afe784de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_3bce8268-aff6-4983-b41d-9dd0dca3f380" xlink:to="loc_us-gaap_SubsequentEventMember_a2b2f9d9-3195-4a62-bfaf-f2e1afe784de" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
