quack

noun

1. The vocalisation made by a duck.

   “Did you hear that duck make a quack?”

   “Twice a day she took them out to feed in the marshy places, let them waddle and gobble for an hour or two, and then drove them back and shut them up in a small dark shed to digest their meal, whence they gave forth occasionally a melancholy quack.”

2. (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 patients

   “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, [...]”

   “‘if we are ourselves valets, there shall ‘exist no hero for us; we shall not know the hero when we see him;’ - we shall take the quack for a hero; and cry, audibly through all ballot-boxes and machinery whatsoever, Thou art he; be thou King over us!”

   “The advertising quack who wearies / With tales of countless cures, / His teeth, I've enacted, / Shall all be extracted / By terrified amateurs.”

3. (derogatory, figuratively)Any similar charlatan or incompetent professional.

   “The very quaik of faſhions, the very hee that / VVeares a Steletto on his chinne.”

4. (derogatory, humorous, mildly, slang)Any doctor.

   “That quack wants me to quit smoking, eat less, and start exercising. The nerve!”

verb

1. Of a duck, to make its characteristic vocalisation.

   “The more breadcrumbs I threw on the ground, the more they quacked.”

   “Do you hear the ducks quack?”

2. To make a sound similar to the quack of a duck.
3. (intransitive)Of a queen bee: to make a high-pitched sound during certain stages of development.
4. To practice or commit quackery (fraudulent medicine).

   “[…] it is incredible, and scarce to be imagin’d, how the Posts of Houses, and Corners of Streets were plaster’d over with Doctors Bills, and Papers of ignorant Fellows; quacking and tampering in Physick, and inviting the People to come to them for Remedies;”

5. (obsolete)To make vain and loud pretensions.

   “Seek out for Plants with Signatures To Quack of Universal Cures”

intj

1. A duck's quack.

adj

1. Falsely presented as having medicinal powers.

   “Don't get your hopes up; that's quack medicine!”

   “In precisely the same way does a quack doctor prescribe his infallible nostrum to every patient, without taking into account differences of constitution, or [...]”

   “[R]ecently I examined as many newspapers and magazines as I could lay hands on just to see if I could find in them those old, alluring advertisements, ranging from the quack doctor to the quacker promoter and the quackest oracle of fate. There was nothing doing—everything as clean as a hound's tooth and as wholesome as sunshine.”

   “Finding, perhaps, that there is no solution either in politics or in any existing religion, he [the common man] may cling to the diagnosis of the last and quackest of his doctors: he may believe that art can save himself and the world.”

   “When no certain cure exists, quack remedies tend to proliferate and the history of quackery and secret cures is full of extraordinary forms of treatment for the various arthritic disorders.”