'quack' originates from the Dutch word 'kwakzalver', where 'kwak' meant 'boast' and 'zalver' meant 'ointment'.

'kwakzalver' transformed into the English word 'quacksalver', and eventually became the modern English word 'quack'.

Initially, it meant 'a person who boasts about their ointments', but over time it evolved into its current meaning of 'a fraudulent or ignorant pretender to medical skill'.