Illustrious people seem to light up everything around them. The etymology of illustrious makes it clear that a shining glow (both literal and figurative) has long been associated with the word. Illustrious derives from the Latin illustris, which was probably a back-formation of the verb illustrare ("to illustrate"), which in turn comes from lustrare, meaning "to purify" or "to make bright," and which is related to the Latin noun lustrum that gave us luster. At one time, illustrious was used in the literal sense of "shining brightly with light," but that meaning is now considered archaic. The word is today almost exclusively used in its figurative application to describe something that stands out brilliantly, much like a bright star stands out in the sky.