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down quark

noun Physics.

the quark having electric charge −1/3 times the elementary charge, with strangeness, charm, and other quark quantum numbers equal to 0.

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Origin of down quark

First recorded in 1975–80
Also called d quark.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Science definitions for d quark

down quark

[doun]

A quark with a charge of -1/3. Its mass is greater than that of the electron and the up quark, but smaller than that of all the other quarks. See Table at subatomic particle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.