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

'approbate' changed from Latin 'approbare' (and the past participle 'approbatus') through Medieval/Late Latin into Early Modern English as 'approbate', retaining the sense of giving assent or approval.

Initially it carried the sense 'to test or prove' and 'to assent/approve'; over time the meaning focused on giving formal or official approval and sanction.