'frown' originates from Old French, specifically the word 'froignier,' where 'froigne' meant 'to wrinkle the brow.'

'froignier' transformed into the Middle English word 'frounen,' and eventually became the modern English word 'frown'.

Initially, it meant 'to wrinkle the brow,' but over time it evolved into its current meaning of 'to show displeasure or disapproval.'