/ Dictionary / Index P polyatomic: Meaning and Definition of Find definitions for: pol•y•a•tom•ic Pronunciation: (pol"ē-u-tom'ik), [key] — adj. Chem. pertaining to a molecule containing more than two atoms. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: polyatomic (Thesaurus) polyarticular polybasic Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language