'authorise' originates from Late Latin, specifically the word 'authorizare', where 'auctor' meant 'originator' or 'giver of authority' and the suffix '-izare' meant 'to make or do (to cause to be).'.

'authorise' changed from Old French 'autoriser' and Middle English 'autorisen' and eventually became the modern English forms 'authorise' (British) and 'authorize' (American).

Initially it meant 'to make authoritative' or 'to appoint with authority'; over time it narrowed to the current meaning 'to give official permission or approval'.