verb Of a duck, to make its characteristic vocalisation.
The more breadcrumbs I threw on the ground, the more they quacked.
verb To make a sound similar to the quack of a duck.
verb Of a queen bee: to make a high-pitched sound during certain stages of development.
interjection A duck's quack.
noun 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 patients .mw-parser-output .defdate{font-size:smaller}
That doctor is nothing but a lousy quack!
noun Any similar charlatan or incompetent professional.
noun Any doctor.
That quack wants me to quit smoking, eat less, and start exercising. The nerve!