blackout

Short definition from Wiktionary

Noun

1. 1
   A temporary loss of consciousness.
2. 2
   A temporary loss of memory.
3. 3
   A large-scale power failure, and resulting loss of electricity to consumers.
4. 4
   An instance of censorship, especially a temporary one.
5. 5
   An intentional outage of a website or other online service, typically as a form of protest.
6. 6
   The mandatory blocking of all light emanating from buildings, as well as outdoor and street lighting as a measure against aerial bombing or naval attack, as imposed during, e.g., World War II.
7. 7
   The blocking out of as much light as possible.
8. 8
   A mass murder committed, usually in an urban area, to eliminate potential witnesses of a previous crime.

Verb

1. 1
   Alternative form of black out.