quack

1 of 5

verb (1)

ˈkwak 

quacked; quacking; quacks

intransitive verb

: to make the characteristic cry of a duck

quack

2 of 5

noun (1)

: a noise made by quacking

quack

3 of 5

verb (2)

quacked; quacking; quacks

intransitive verb

: to act like a quack

quack

4 of 5

noun (2)

1

: charlatan sense 2

Religious quacks on radio and television thinking up new ways to take money from ignorant listeners and incidentally from legitimate churches.

—Andrew A. Rooney

2

: an ignorant, misinformed, or dishonest practitioner of medicine

No doubt these misunderstandings and dashed hopes have driven many cancer patients and their families into the arms of quacks.

—Haydn Bush

quackish

ˈkwa-kish 

adjective

quack

5 of 5

adjective

: of, relating to, or used by quacks

quack cancer cures

Synonyms of quack

Noun (2)

• fraud
• fake
• sham
• charlatan
• pretender
• mountebank
• faker
• deceiver
• misleader
• impostor

Examples of quack in a Sentence

Noun (2)

don't bother to see that guy, as I've heard he's a quack with no actual training

Recent Examples on the Web

Verb

But man, these Mets certainly have quacked like a duck so far. — Tony Blengino, Forbes.com, 14 Apr. 2026

In video shared on social media by the RPD, the ducklings can be heard quacking loudly amid the rescue. — Lexi Lane, PEOPLE, 26 Apr. 2026

Noun

Automatic ducking doesn't add quacks to your soundtrack. — PC Magazine, 15 Nov. 2025

And this is why hydropathy was not like many of the other quack medical therapies of the not-quite-modern era. — John Jeremiah Sullivan, Harpers Magazine, 29 Apr. 2025

Adjective

Cure-all claims are one of the foremost signs of quack medicines. — David Reamer, Anchorage Daily News, 2 Jan. 2023

Junk shops are portals to mythological realms, and religious visions emerge from quack medicine ads. — Robert Rubsam, Washington Post, 2 May 2023

Word History

Etymology

Verb (1)

alteration of queck to quack, from Middle English queken, from queke, interjection, of imitative origin

Noun (2) and Verb (2)

short for quacksalver

First Known Use

Verb (1)

1570, in the meaning defined above

Noun (1)

1806, in the meaning defined above

Verb (2)

1650, in the meaning defined above

Noun (2)

1638, in the meaning defined at sense 1

Adjective

1670, in the meaning defined above

Phrases Containing quack

• quack grass

Rhymes for quack

• ack
• brack
• clack
• crack
• dak
• flack
• flak
• hack
• jack
• knack
• lac
• lack

Kids Definition

quack

1 of 4 noun

ˈkwak 

: the cry of a duck

also : a sound resembling this cry

quack

2 of 4 verb

: to make a quack

quack

3 of 4 noun

: a person who makes false claims to special knowledge or ability

especially : one who pretends to have medical skill

quack

4 of 4 adjective

: of, relating to, or used by a person who is a quack

quack medicines

Etymology

Noun

a word created to imitate the sound made by a duck

Noun

a shortened form of earlier quacksalver "a person who pretends to have medical skill"; of Dutch origin

Medical Definition

quack

1 of 2 noun

ˈkwak 

: a pretender to medical skill : an ignorant or dishonest practitioner

quackish

-ish 

adjective

quack

2 of 2 adjective

: of, relating to, characteristic of, or being a quack

scores of quack remedies for arthritis

—Jane E. Brody