a. The act of illuminating.
b. The state of being illuminated.
2. A source of light.
3. Decorative lighting.
4. Spiritual or intellectual enlightenment.
5. Clarification; elucidation.
a. The art or act of decorating a text, page, or initial letter with ornamental designs, images, or lettering.
b. An example of this art.
7. Physics The luminous flux per unit area at any point on a surface exposed to incident light. Also called illuminance.
(click for a larger image)illumination
folio from the 14th-century illuminated manuscript Jami' al-tawarikh by Rashid al-Din (1247-1318)
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.