'approval' originates from Latin, specifically the word 'approbare,' where 'ad-' (later assimilated to 'ap-') meant 'to/toward' and 'probare' meant 'to test, prove, approve.'

'approbare' passed into Old French as 'aprover' / 'approuver' and Medieval Latin 'approbatio' / Old French 'aprobacion,' then into Middle English as 'approbacioun'/'approval,' eventually becoming the modern English 'approval.'

Initially related to 'testing' or 'proving' (to demonstrate as good or correct); over time it shifted to the sense of expressing favorable judgment or granting permission — the modern meaning of 'formal consent or favorable opinion.'