/ Dictionary / Index A antiproton: Meaning and Definition of Find definitions for: an•ti•pro•ton Pronunciation: (an'tē-prō"ton, an'tī-), [key] — n. Physics. an elementary particle having negative charge equal in magnitude to that of the electron and having the same mass and spin as a proton; the antiparticle of the proton. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: antiproton (Thesaurus) antiproliferative antipruritic Related Content Daily Word Quiz: lyceum Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language