Named by: Murray Gell-Mann, 1963

Quarks are elementary particles that form hadrons such as protons and neutrons, as well as more exotic particles and states of matter like quark-gluon plasma. They were proposed simultaneously by Murray Gell-Mann and George Zweig (who wanted to call them “aces”), and different types of quarks were discovered throughout the rest of the 20th century by multiple different teams of physicists.

Gell-Man wrote about the name in his popular science book The Quark and the Jaguar:

In 1963, when I assigned the name “quark” to the fundamental constituents of the nucleon, I had the sound first, without the spelling, which could have been “kwork.” Then, in one of my occasional perusals of Finnegans Wake, by James Joyce, I came across the word “quark” in the phrase “Three quarks for Muster Mark”. Since “quark” (meaning, for one thing, the cry of the gull) was clearly intended to rhyme with “Mark,” as well as “bark” and other such words, I had to find an excuse to pronounce it as “kwork.” But the book represents the dream of a publican named Humphrey Chimpden Earwicker. Words in the text are typically drawn from several sources at once, like the “portmanteau” words in Through the Looking-Glass. From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar. I argued, therefore, that perhaps one of the multiple sources of the cry “Three quarks for Muster Mark” might be “Three quarts for Mister Mark,” in which case the pronunciation “kwork” would not be totally unjustified. In any case, the number three fitted perfectly the way quarks occur in nature.

Some scholars suspect that the quark in Joyce’s epic derives from the German quark, which is a type of cheese curd. The German quark is likely taken from West Slavic words meaning “to form”—potentially a reference to milk solidifying and becoming curd. Serendipitously, “to form” is also the non-dairy quark’s role as the main constituent of matter.

Physicists have discovered six types of quarks, named “up,” “down,” “strange,” “charm,” “top” and “bottom.”

up and down quarks: Gell-Mann named these quarks in 1964 for their upward and downward isospin, which is a quantum property of particles related to the strong nuclear force.

strange: Unlike up and down quarks, strange quarks were observed before the quark model was developed, as constituents of composite particles called kaons. These particles were deemed "strange" because they had unusually long lifetimes, due to some of their decays occurring through the weak force. Gell-Man called them “strange” quarks in 1964.

charm: The charm quark was predicted in a paper by two physicists, Sheldon Glashow and James Bjorken, in 1964. As they explained in a New York Times article: “We called our construct the ‘charmed quark,’ for we were fascinated and pleased by the symmetry it brought to the subnuclear world.” “Charm,” meaning “pleasing quality,” is derived from the Latin carmen, “song, verse, enchantment.”

top and bottom: Physicists Makoto Kobayashi and Toshihide Maskawa predicted the existence of the last two quarks in 1973, but they did not assign names to the new particles. Many scientists unofficially called them “truth” and “beauty.”

In a 1975 paper, physicist Haim Harari gave them names that stuck. To preserve the initials “t” and “b” and create a fitting counterpart for up and down quarks, Harari called them “top” and “bottom” quarks.