'assecure' originates from Anglo-French, specifically the word 'assecurer', where the prefix 'as-' (from Latin 'ad-') meant 'to/toward' and the root 'secur-' came from Latin 'securus' meaning 'safe'.

'assecure' changed from Anglo-French 'assecurer' and Middle English forms such as 'assecuren', and eventually appeared in modern English as 'assecure' (now rare/archaic).

Initially, it meant 'to make safe or secure'; over time it came to be used also in the sense 'to guarantee or insure', and in modern usage the word has largely become archaic or replaced by 'secure', 'assure', or 'ensure'.