/ Dictionary / Index R Rb: Meaning and Definition of Find definitions for: Rb Pronunciation: [key] — Symbol, Chem. rubidium. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rb (Thesaurus) razzmatazz RBC Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language