'approvableness' originates from Late Latin, specifically the word 'approbāre', where the prefix 'ad-' (in compounds becoming 'ap-') meant 'to/toward' and 'probare' meant 'to test, prove, or approve'.

'approvableness' developed via Old French and Middle English forms related to 'approbable' and 'approve' (Old French 'aprover', Middle English 'approven'/'approbaren'), and the modern English noun was formed by adding the nominalizing suffix '-ness' to the adjective 'approvable'.

Initially the Latin root meant 'to test or prove' (hence to give assent after examination); over time this evolved into the narrower modern sense of 'to approve', and 'approvableness' now denotes the quality of being able to be approved.