1520s, "light up, shed light on;" 1610s, "educate by means of examples," back-formation from illustration, and in some cases from Latin illustratus, past participle of illustrare "light up, make light, illuminate." Sense of "provide pictures to explain or decorate" is 1630s. Related: Illustrated; illustrating.
illustrate a book with drawings
illusion
illusionary
illusionist
illusive
illusory
illustrate
illustrated
illustration
illustrative
illustrator
illustrious