/ Dictionary / Index B B particle: Meaning and Definition of Find definitions for: B particle Pronunciation: [key] — Physics. Physics. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. B.P.A. BPD Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language