Blackout: the extinguishing or concealment of all visible lights in a city, military post, etc. usually as a precaution against air raids; complete stoppage of a communications medium, as by a strike, catastrophe, electrical storm/force majeure.

Blackout: the extinguishing or concealment of all visible lights in a city, military post, etc. usually as a precaution against air raids; complete stoppage of a communications medium, as by a strike, catastrophe, electrical storm/force majeure.