from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A quark with a charge of + 2/3 and a mass about 607 times that of the electron. It is a component of protons and neutrons. See Table at subatomic particle.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A quark having a fractional electric charge of +2/3 and a mass of about 1.5 to 4 MeV. Symbol: u
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a stable quark with an electric charge of +2/3 and a mass 607 times that of an electron
Sorry, no etymologies found.