/kwɑ:k; kwɑrk/
n (physics 物) any of several very small parts of which elementary particles are thought to consist 夸克（组成基本粒子的更小的粒子）.

n[C]
[Date: 1900-2000; Origin: Invented by Murray Gell-Mann (born 1929), U.S. scientist, based on the phrase "three quarks for Muster Mark" in Finnegans Wake (1939) by James Joyce; because originally there were thought to be three quarks]
technical a very small part of something, which is smaller than an atom