/ Dictionary / Index P pi meson: Meaning and Definition of Find definitions for: pi' me'son Pronunciation: [key] — Physics. Physics. pion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pimento cheese pimiento Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language