'authorisation' originates from Medieval Latin/Late Latin, specifically the word 'authorizare' (via Old French 'autorisation'), where 'auctor' meant 'originator' or 'author'.

'authorisation' changed from the Old French/Latin word 'autorisation'/'authorizare' and entered English through Anglo-Norman and Middle English, eventually becoming the modern English word 'authorisation'.

Initially, related forms meant 'to make someone an author or to give authority'; over time it evolved into the current sense of 'giving official permission' or 'formal consent'.