'fault' originates from Old French, specifically the word 'faute', where 'faute' meant 'lack, error' (Old French). It was later used in Middle English as 'faute'/'fault'.

'fault' changed from Old French 'faute' (from Vulgar Latin past participle *fallita) into Middle English forms 'faute' or 'fault' and eventually became the modern English word 'fault'.

Initially, it meant 'a failing, lack or error' but over time it evolved to include meanings of 'blame' or 'responsibility' and later acquired a specialized geological sense of 'a break or fracture in rock'.