'assure' originates from Old French, specifically the word 'asseurer,' where 'a-' meant 'to' and 'seur' meant 'secure.'

'asseurer' transformed into the Middle English word 'assuren,' and eventually became the modern English word 'assure.'

Initially, it meant 'to make secure or safe,' but over time it evolved into its current meaning of 'to make certain or to guarantee.'