A temporary loss of consciousness.

A temporary loss of memory.

A large-scale power failure, and resulting loss of electricity to consumers.

An instance of censorship, especially a temporary one.

(Internet) An intentional outage of a website or other online service, typically as a form of protest.

(historical) 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.

(attributive) The blocking out of as much light as possible.

(slang, criminology, rare) A mass murder committed, usually in an urban area, to eliminate potential witnesses of a previous crime.

(nonstandard) Alternative form of black out