tr.v. il·lu·mi·nat·ed, il·lu·mi·nat·ing, il·lu·mi·nates
1. To provide or brighten with light.
2. To decorate or hang with lights.
a. To make understandable; clarify: "Cleverly made attacks can ... serve to illuminate important differences between candidates" (New Republic).
b. To enlighten intellectually or spiritually; enable to understand: "I greatly misdoubt the accuracy of this ... Can you illuminate me?" (Charles Darwin).
4. To adorn (a page of a book, for example) with ornamental designs, images, or lettering in brilliant colors or precious metals.
5. To expose to or reveal by radiation.
One who has or professes to have an unusual degree of enlightenment.
[Middle English illuminaten, from Latin illūmināre, illūmināt- : in-, in; see IN-2 + lūmināre, to light up (from lūmen, lūmin-, light; see leuk- in the Appendix of Indo-European roots).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.