/ Dictionary / Index R riebeckite: Meaning and Definition of Find definitions for: rie•beck•ite Pronunciation: (rē'be-kīt"), [key] — n. an amphibolic mineral, silicate of sodium and iron, occurring usually in feldspathoid rocks. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ridotto Riefenstahl Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language