Search Result for "up quark":
Wordnet 3.0

NOUN (1)

1. a stable quark with an electric charge of +2/3 and a mass 607 times that of an electron; 



WordNet (r) 3.0 (2006):

up quark
    n 1: a stable quark with an electric charge of +2/3 and a mass
         607 times that of an electron