WordNet (r) 3.0 (2006):

quark
    n 1: (physics) hypothetical truly fundamental particle in mesons
         and baryons; there are supposed to be six flavors of quarks
         (and their antiquarks), which come in pairs; each has an
         electric charge of +2/3 or -1/3; "quarks have not been
         observed directly but theoretical predictions based on
         their existence have been confirmed experimentally"
    2: fresh unripened cheese of a smooth texture made from
       pasteurized milk, a starter, and rennet [syn: quark cheese,
       quark]