/ Dictionary / Index Q quarkonium: Meaning and Definition of Find definitions for: quar•ko•ni•um Pronunciation: (kwôr-kō'nē-um, kwär-), [key] — n. Physics. a meson composed of a quark and an antiquark of the same flavor. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. quark model Quarles Related Content Daily Word Quiz: philtrum Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language