'compliancy' ultimately originates from Old French and Latin roots; it is related to Old French 'compliance' (willingness, agreement), from Latin 'complacēre', where 'com-' meant 'together' and 'placēre' meant 'to please'.

'compliancy' developed from Middle English forms of 'compliance' (borrowed from Old French 'compliance') and later formed as the noun 'compliancy' in Modern English to denote the state or quality of being compliant.

Initially connected with the idea of 'pleasing' or 'agreeing' (from Latin 'complacēre'), the sense shifted toward 'yielding or conforming to requests/rules', resulting in the modern meaning 'readiness or conformity to comply'.