2.  a period during a massive power failure when the lack of electricity for illumination results in utter darkness except from emergency sources, as candles.

3.  Theater .
     a.  the extinguishing of all stage lights, as in closing a vaudeville skit or separating the scenes of a play.
     b. Also called blackout skit . a skit ending in a blackout.

4. Pathology .
     a.  temporary loss of consciousness or vision: She suffered a blackout from the blow on the head.
     b.  a period of total memory loss, as one induced by an accident or prolonged alcoholic drinking: The patient cannot account for the bizarre things he did during his blackout.

5.  a brief, passing lapse of memory: An actor may have an occasional blackout and forget a line or two.

6.  complete stoppage of a communications medium, as by a strike, catastrophe, electrical storm, etc.: a newspaper blackout; a radio blackout.

7.  a stoppage, suppression, or obliteration: a news blackout.

8.  a period during which  a special sales offer, fare rate, or other bargain is not available: The airline’s discount on fares does not apply during the Christmas week blackout.

9.  Radio and Television . a prohibition that is imposed on the broadcasting of an event and has the purpose of encouraging or ensuring ticket sales.