/ Dictionary / Index R radium B: Meaning and Definition of Find definitions for: radium B Pronunciation: [key] — Chem. Chem. an isotope of lead, formed by decay of radium A, that gives rise to radium C, which is an isotope of bismuth, from which radium D, radium E, and radium F, or polonium 210, are derived. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radium A radium emanation Related Content Daily Word Quiz: abominable Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language