/ Dictionary / Index I illustrious: Meaning and Definition of Find definitions for: il•lus•tri•ous Pronunciation: (i-lus'trē-us), [key] — adj. highly distinguished; renowned; famous: an illustrious leader. glorious, as deeds or works: many illustrious achievements. luminous; bright. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: illustrious (Thesaurus) illustrator illuvial Related Content Daily Word Quiz: penury Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language