- A cutoff of electrical power, especially as a result of a shortage, a mechanical failure, or overuse by consumers.
- The concealment or extinguishment of lights that might be visible to enemy aircraft during an air raid.
- 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.
- A short, comic vaudeville skit that ends with lights off.
- A temporary loss of memory or consciousness.
- A suppression, as of news, by censorship.
- Restriction or prohibition of telecasting a sports event in order to ensure ticket sales.