/ Dictionary / Index D diatomic: Meaning and Definition of Find definitions for: di•a•tom•ic Pronunciation: (dī"u-tom'ik), [key] — adj. Chem. having two atoms in the molecule. containing two replaceable atoms or groups; binary. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diatomic (Thesaurus) diatomaceous earth diatonic 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