/ Dictionary / Index S sodium sulfite: Meaning and Definition of Find definitions for: so'dium sul'fite Pronunciation: [key] — Chem. Chem. a white, crystalline, water-soluble solid, NaSO, used chiefly as a food preservative, as a bleaching agent, and as a developer in photography. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sodium sulfide sodium tetraborate Related Content Daily Word Quiz: illegible Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language