/ Dictionary / Index S suboxide: Meaning and Definition of Find definitions for: sub•ox•ide Pronunciation: (sub-ok'sīd, -sid), [key] — n. Chem. the oxide of an element that contains the smallest proportion of oxygen. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Subotica subphylum Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language