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up quark

noun, Physics.
1.
the quark having electric charge 2/3 times the elementary charge and strangeness and charm equal to 0.
Also called u quark.
Origin
1975-1980
1975-80
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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up-quark in Science
up quark
  (ŭp)   
A quark with a charge of +2/3. Its mass is approximately 10 times the electron mass and is the least mass of all quarks. See Table at subatomic particle.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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