tr.v. en·light·ened, en·light·en·ing, en·light·ens
1. To give spiritual or intellectual insight to: "Enlighten the people generally, and tyranny and oppression of body and mind will vanish like evil spirits at the dawn of day" (Thomas Jefferson).
2. To give information to; inform or instruct.
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.