illustrious (adj.) Look up illustrious at Dictionary.com
1560s, "distinguished by greatness, renowned," from Latin illustris "lighted, bright, brilliant;" figuratively "distinguished, famous," probably a back-formation from illustrare "make light, light up, illuminate," figuratively "embellish, distinguish, make famous" (see illustration). Replaced illustre in same sense (mid-15c.), from Middle French illustre.