/ Dictionary / Index B B meson: Meaning and Definition of Find definitions for: B meson Pronunciation: [key] — Physics. Physics. a meson composed of a bottom quark and an up or down antiquark or of a bottom antiquark and an up or down quark. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. B.M.Ed. B.Met. Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language