/ Dictionary / Index R radii: Meaning and Definition of Find definitions for: ra•di•i Pronunciation: (rā'dē-ī"), [key] — n. a pl. of Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: radii (Thesaurus) radiculitis Radin Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language