quark

American  

[kwawrk, kwahrk] / kwɔrk, kwɑrk /

noun

1. Physics. any of the particles with spin 1/2, baryon number 1/3, and electric charge 1/3 or −2/3 that, together with their antiparticles, are believed to constitute all the elementary particles classed as baryons and mesons; they are distinguished by their flavors, designated as up (u), down (d), strange (s), charm (c), bottom or beauty (b), and top or truth (t), and their colors, red, green, and blue.

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quark ¹ British  

/ kwɑːk /

noun

1. physics any of a set of six hypothetical elementary particles together with their antiparticles thought to be fundamental units of all baryons and mesons but unable to exist in isolation. The magnitude of their charge is either two thirds or one third of that of the electron

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quark ² British  

/ kwɑːk /

noun

1. a type of low-fat soft cheese

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quark Scientific  

/ kwôrk,kwärk /

1. Any of a group of elementary particles supposed to be the fundamental units that combine to make up the subatomic particles known as hadrons (baryons, such as neutrons and protons, and mesons). There are six different flavors (or types) of quark: up quark, down quark, top quark, bottom quark, charm quark, and strange quark. Quarks have fractional electric charges, such as 1/3 the charge of an electron.

2. See Note at elementary particle See Table at subatomic particle

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Etymology

Origin of quark

Coined in 1963 by U.S. physicist Murray Gell-Mann (1929–2019), who associated it with a word in Joyce's Finnegans Wake, read variously as English quark croak and German Quark curd, (slang) rubbish, tripe

Explanation

A quark is an elementary particle with an electric charge. When quarks combine, they form another type of particle called a "hadron." If you want to learn more, take up particle physics. Quarks are held together by what physicists call "the strong force" or "the strong nuclear force." The most stable of these quark combinations, or hadrons, are protons and neutrons — the basic building blocks of atoms. In the 1960s, a physicist named Murray Gell-Mann named these particles from a favorite made-up word in James Joyce's book Finnegan's Wake: quark. Gell-Mann's partner reportedly preferred the word ace.

Example Sentences

One promising approach involves mesons, which are particles made of a quark and an anti-quark, bound together with an atomic nucleus.

From Science Daily • Apr. 25, 2026

Normal protons have two "up" quarks and one "down" quark.

From Barron's • Mar. 17, 2026

My father, who was a physicist, said if someone can’t define a quark in less than 30 seconds, they don’t know what they’re talking about.

From The Wall Street Journal • Nov. 6, 2025

The names for these speculative particles often tack on an S to the names of known particles: selectrons contrast electrons, the squark is the inverted twin of the quark, and so on.

From Salon • Dec. 26, 2024

“Well, I know a quark is a subatomic particle, but if you ask me, it also sounds like the noise a subatomic duck might make.”

From "Shine!" by J.J. and Chris Grabenstein