- highly distinguished; renowned; famous: an illustrious leader.
- glorious, as deeds or works: many illustrious achievements.
- Obsolete. luminous; bright.
- of great renown; famous and distinguished
- glorious or greatillustrious deeds
- obsolete shining
1560s, from Latin illustris “lighted, bright, brilliant;” figuratively “distinguished, famous,” probably a back-formation from illustrare “embellish, distinguish, make famous” (see illustration). Sometimes also illustrous. Replaced illustre in same sense (mid-15c.), from Middle French illustre.