/ Dictionary / Index M monatomic: Meaning and Definition of Find definitions for: mon•a•tom•ic Pronunciation: (mon"u-tom'ik), [key] — adj. Chem. having one atom in the molecule. containing one replaceable atom or group. having a valence of one. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: monatomic (Thesaurus) Monastir monaural Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language