'affiance' originates from Old French, specifically the word 'afiancer,' where 'a-' meant 'to' and 'fiance' meant 'trust or promise.'

'afiancer' transformed into the Middle English word 'affiencen,' and eventually became the modern English word 'affiance.'

Initially, it meant 'to trust or promise,' but over time it evolved into its current meaning of 'to betroth or engage in marriage.'