/ Dictionary / Index R radium sulfate: Meaning and Definition of Find definitions for: ra'dium sul'fate Pronunciation: [key] — Chem. Chem. a white, crystalline, water-insoluble, poisonous, radioactive solid, RaSO, used chiefly in radiotherapy. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radium F radium therapy Related Content Daily Word Quiz: longevity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language