/ Dictionary / Index R red-letter: Meaning and Definition of Find definitions for: red-let•ter Pronunciation: (red'let'ur), [key] — adj. marked by red letters, as festival days in the church calendar. memorable; especially important or happy: a red-letter day in his life. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: red-letter (Thesaurus) redlegged grasshopper red light Related Content Daily Word Quiz: dissonant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language