'fool' originates from Old French, specifically the word 'fol', which in turn comes from Latin 'follis' meaning 'bellows' or 'an inflated bag'.

'fool' changed from Middle English forms such as 'fol' or 'fole' and eventually became the modern English word 'fool'.

Initially, it referred to an 'inflated thing' (Latin 'follis'), but over time it evolved into the meaning 'a person lacking good sense' in modern English.