1. A cutoff of electric power, especially as a result of a shortage, a mechanical failure, or overuse by consumers.
2. The concealment or extinguishment of lights that might be visible to enemy aircraft during an air raid.
a. The sudden extinguishment of all stage lights in a theater to indicate the passage of time or to mark the end of an act or scene.
b. A short, comic vaudeville skit that ends with lights off.
4. A temporary loss of memory or consciousness.
a. A suppression, as of news, by censorship.
b. A suppression of the broadcast of an event or program, as to support ticket sales at a local venue.
6. A suspension of a discounted price or free offer, as for an airline ticket or a lift ticket at a ski resort.
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.