Dictionary.com
Thesaurus.com
Synonyms

knockout

American  
[nok-out] / ˈnɒkˌaʊt /

noun

  1. an act or instance of knocking out.

  2. the state or fact of being knocked out.

  3. a knockout blow.

  4. Informal. a person or thing overwhelmingly attractive, appealing, or successful.

  5. a panel in a casing, can, or box, especially of metal or plastic, so designed that it can readily be removed, as by punching, hammering, or cutting, to provide an opening into the interior.

    a knockout in a junction box.

  6. Machinery. a device for knocking something loose, as finished work from a lathe chuck.


adjective

  1. that knocks out.

    the knockout punch.

knockout British  
/ ˈnɒkˌaʊt /

noun

  1. the act of rendering unconscious

  2. a blow that renders an opponent unconscious

    1. a competition in which competitors are eliminated progressively

    2. ( as modifier )

      a knockout contest

  3. a series of absurd invented games, esp obstacle races, involving physical effort or skill

  4. informal a person or thing that is overwhelmingly impressive or attractive

    she's a knockout

"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

verb

  1. to render unconscious, esp by a blow

  2. boxing to defeat (an opponent) by a knockout

  3. to destroy, damage, or injure badly

  4. to eliminate, esp in a knockout competition

  5. informal to overwhelm or amaze, esp with admiration or favourable reaction

    I was knocked out by that new song

  6. to remove the ashes from (one's pipe) by tapping

"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

Etymology

Origin of knockout

1810–20; 1935–40 knockout for def. 4; noun, adj. use of verb phrase knock out