'assurer' originates from Old French, specifically the word 'asseurer', where the prefix 'as-' (from Latin 'ad-') meant 'to' and 'seurer' (from Late Latin 'securus') meant 'secure'.

'assurer' changed from Old French 'asseurer' into Middle English forms such as 'assuren'/'assure' and eventually developed into the modern English noun 'assurer'.

Initially, it meant 'to make secure or safe', but over time it evolved into its current meanings of 'to make someone confident, to guarantee, or to provide assurance'.