quack

1. (derogatory) A fraudulent healer, especially a bombastic peddler in worthless treatments, a doctor who makes false diagnoses for monetary benefit, or an untrained or poorly trained doctor who uses fraudulent credentials to attract patientsExamples: "That doctor is nothing but a lousy quack!"; "1662, Rump: or an Exact Collection of the Choycest Poems and Songs Relating to Late Times, Vol. II, by ‘the most Eminent Wits’ Tis hard to say, how much these Arse-wormes do urge us, We now need no Quack but these Jacks for to purge us, …"; "After ſome Months, the Quack gets privately to Town, [...]"derogatory

2. (figuratively, derogatory) Any similar charlatan or incompetent professional.Examples: "The very quaik of faſhions, the very hee that / VVeares a Steletto on his chinne."derogatoryfiguratively

3. (humorous slang, mildly derogatory) Any doctor.Examples: "That quack wants me to quit smoking, eat less, and start exercising. The nerve!"derogatoryhumorousmildlyslang

1. (obsolete) To make vain and loud pretensions.Examples: "Seek out for Plants with Signatures To Quack of Universal Cures"Synonyms: boastobsolete