/ Dictionary / Index D dioxide: Meaning and Definition of Find definitions for: di•ox•ide Pronunciation: (dī-ok'sīd, -sid), [key] — n. Chem. an oxide containing two atoms of oxygen, each of which is bonded directly to an atom of a second element, as manganese dioxide, MnO, or nitrogen dioxide, NO. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: dioxide (Thesaurus) dioxane dioxin Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language