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[blak-out] /ˈblækˌaʊt/
the extinguishing or concealment of all visible lights in a city, military post, etc., usually as a precaution against air raids.
a period during a massive power failure when the lack of electricity for illumination results in utter darkness except from emergency sources, as candles.
  1. the extinguishing of all stage lights, as in closing a vaudeville skit or separating the scenes of a play.
  2. Also called blackout skit. a skit ending in a blackout.
  1. temporary loss of consciousness or vision:
    She suffered a blackout from the blow on the head.
  2. 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.
a brief, passing lapse of memory:
An actor may have an occasional blackout and forget a line or two.
complete stoppage of a communications medium, as by a strike, catastrophe, electrical storm, etc.:
a newspaper blackout; a radio blackout.
a stoppage, suppression, or obliteration:
a news blackout.
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.
Radio and Television. a prohibition that is imposed on the broadcasting of an event and has the purpose of encouraging or ensuring ticket sales.
Origin of blackout
First recorded in 1910-15; noun use of verb phrase black out
Can be confused
blackout, brownout. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for blackout


the extinguishing or hiding of all artificial light, esp in a city visible to an enemy attack from the air
a momentary loss of consciousness, vision, or memory
a temporary electrical power failure or cut
(electronics) a temporary loss of sensitivity in a valve following a short strong pulse
a temporary loss of radio communications between a spacecraft and earth, esp on re-entry into the earth's atmosphere
the suspension of radio or television broadcasting, as by a strike or for political reasons
verb (adverb)
(transitive) to obliterate or extinguish (lights)
(transitive) to create a blackout in (a city etc)
(intransitive) to lose vision, consciousness, or memory temporarily
(transitive, adverb) to stop (news, a television programme) from being released or broadcast
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for blackout

also black-out, 1908 in the theatrical sense of a darkened stage, from black + out. Figurative sense of "loss of memory" is 1934 (verb and noun); as a dousing of lights as an air raid precaution, it is recorded from 1935. Verbal phrase black out, in reference to printed or written matter deemed objectionable and covered in black ink, is attested from 1888.

Online Etymology Dictionary, © 2010 Douglas Harper
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blackout in Medicine

blackout black·out (blāk'out')

  1. Temporary loss of consciousness due to decreased blood flow to the brain.

  2. Temporary loss of memory.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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blackout in Culture

blackout definition

The complete loss of electrical power in a particular area. Blackouts can result from a natural disaster, a manmade catastrophe, or simply from an excess of energy demand over supply. (Compare brownout.)

Note: Rolling blackouts to match supply and demand have become increasingly common in the United States.
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for blackout



A period during which discount or favorable prices on airlines are arbitrarily canceled: flight from LA to NYC for free (depending on availability, blackout dates and routings) (1990s+)

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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