/ Dictionary / Index M metacinnabar: Meaning and Definition of Find definitions for: met•a•cin•na•bar Pronunciation: (met"u-sin'u-bär"), [key] — n. Mineral. a polymorph of cinnabar, black mercuric sulfide, HgS. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. metachromatism Metacomet Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language