quack

¹ American  

[kwak] / kwæk /

noun

1. the harsh, throaty cry of a duck or any similar sound.

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verb (used without object)

1. to utter the cry of a duck or a sound resembling it.

quack ² American  

[kwak] / kwæk /

noun

1. a fraudulent or ignorant pretender to medical skill.

   Desperation for a cure led her to a quack who took her money.

2. a person who pretends, professionally or publicly, to have skill, knowledge, or qualifications they do not possess; a charlatan.

   Synonyms:

   phony, mountebank

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adjective

1. being a fraudulent or ignorant pretender to skills, especially medical skills.

   He's just a quack psychologist who complicates everyone's problems.

2. presented falsely as having curative powers.

   quack medicine.

3. of, relating to, or befitting a quack or quackery.

   Her quack methods have helped no one.

verb (used with object)

1. to treat in the manner of a fraudulent or ignorant pretender to medical skill.

2. to advertise or sell with fraudulent claims.

quack ¹ British  

/ kwæk /

noun

1. 1. an unqualified person who claims medical knowledge or other skills

   2. ( as modifier )

      a quack doctor

2. informal a doctor; physician or surgeon

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verb

1. (intr) to act in the manner of a quack

quack ² British  

/ kwæk /

verb

1. (of a duck) to utter a harsh guttural sound

2. to make a noise like a duck

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noun

1. the harsh guttural sound made by a duck

Other Word Forms

• quackish
  adjective
• quackishly
  adverb
• quackishness
  noun

Etymology

Origin of quack¹

First recorded in 1570–80; imitative; compare Dutch kwakken, German quacken

Origin of quack²

First recorded in 1630–40; short for quacksalver

Explanation

There are good quacks and bad quacks. A good quack is the sound a duck makes. A bad quack is someone pretending to be a doctor. (You'd be better off visiting the duck with your ailment.) If you ever get a chance to interview a celebrity duck, prepare to write the word quack in your notebook many, many times, because that’s all that ducks can say. The way you spell animal sounds changes depending what language you speak. In English a duck quacks, but in Danish a duck "raps," while Indonesian ducks "wek," and Romanian ducks say "mac." And that "MD" who isn’t really a doctor, but is good at pretending to be one? He's a quack. If you ever meet a quack that "quacks," please run.

Example Sentences

“The Doctors’ Riot of 1788” centers on the New York incident but also tells the broader story of medicine in the early American republic, including quack cures and smallpox panics.

From The Wall Street Journal • Jan. 5, 2026

There are also medbed clinics, where people can pay to receive quack treatments from people who claim to have working medbeds.

From Slate • Sep. 29, 2025

Where Wayne’s Batman is lithe and graceful, The Penguin is awkward and rotund; while Wayne is charismatic, the Penguin is a weirdo, a quack.

From Salon • Oct. 27, 2024

Each of the three species create very different noises: humpbacks sing complex songs, minkes quack like ducks, and sei whales create low frequency booms.

From National Geographic • Feb. 21, 2024

Mama Duck hiss and snort and cluck and quack up a blue streak.

From "Girls Like Us" by Gail Giles