'affiance' originates from Old French, specifically the word 'affier,' where 'a-' meant 'to' and 'fier' meant 'trust.'

'affier' transformed into the Middle English word 'affien,' and eventually became the modern English word 'affiance.'

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