/ Dictionary / Index S sodium peroxide: Meaning and Definition of Find definitions for: so'dium perox'ide Pronunciation: [key] — Chem. Chem. a yellowish-white, hygroscopic, water-soluble powder, NaO, used chiefly as a bleaching agent and as an oxidizing agent. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sodium perborate sodium phosphate Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language