knockout

Etymology

From knock out.

noun

1. The act of making one unconscious, or at least unable to come back on one's feet within a certain period of time; a TKO.
   The boxer scored a knockout on his opponent.
2. The deactivation of anything.
   Pull the plug on a node to see how the network handles a node knockout. 6 February 1989, Network World, page 82
3. (informal) Something wildly popular, entertaining, or funny.
   If you've ever had a sack race, you know it's a real knockout for kids and adults alike.
4. (informal) A very attractive person, especially a beautiful woman.
   1995, Rhonda K. Reinholtz et al., "Sexual Discourse and Sexual Intercourse," in P. J. Kalbfleisch and M. J. Cody, eds., Gender, Power, and Communications in Human Relationships, p. 150, Phrases such as "she bowled me over," "she's striking," and "she's a knockout" suggest that the woman affects the man in ways he cannot mediate or control.
5. A partially punched opening meant for optional later removal.
   They left a knockout in the panel for running extra wires someday.
6. (genetics) The deactivation of a particular gene.
7. (genetics) A creature engineered with a particular gene deactivated.
8. (printing) An event where a foreground color causes a background color not to print.
9. (sports) A tournament in which a team or player must beat the opponent in order to progress to the next round.
   the knockout stages of the competition
   In truth, Tottenham never really looked like taking all three points and this defeat means they face a battle to reach the knockout stages -with their next home game against PAOK Salonika on 30 November likely to prove decisive. November 3, 2011, Chris Bevan, “Rubin Kazan 1 - 0 Tottenham”, in BBC Sport
10. (uncountable) A simple game for two or more players, derived from basketball.
11. Short for knockout auction.

adj

1. Rendering someone unconscious.
   He delivered a knockout blow.
2. Amazing; gorgeous; beautiful.
   You should have seen her knockout eyes.
   If the same model has beautiful hair, white teeth, glowing skin, a fit body, good hands and legs, a great wardrobe, and a knockout comp, her value on the "bookability meter" goes sky high. 2010, Ro Martinez, Modeling at Any Age, page 81
3. (genetics) Designating an organism in which a particular gene has been removed or deactivated.
   The result is a so-called knockout mouse, reared with a single gene silenced, the better to reveal that gene's true purpose. 1999, Matt Ridley, Genome, Harper Perennial, published 2004, page 255
4. Causing elimination from a competition.
   Rodolph Austin delivered the knockout blow from close range 20 minutes from time, after Aidan White had given Leeds a dream start after four minutes. 2012, Ben Smith, Leeds United 2-1 Everton