Blackout

The term "blackout" refers to a cessation of electromagnetic activity.

• collectively minimizing external light (during war), especially upwards directed (or reflected) light, to "hide" from enemy aircraft (in the case of an occupied country: the enemy of the occupying force)
• large-scale power failure
• short dysfunctioning of the brain (loss of consciousness or not being able to think well)

See also communications blackout.