A knockout (abbreviated to KO or K.O.) is a fight-ending, winning criterion in several full-contact combat sports, such as boxing, kickboxing, Muay Thai, mixed martial arts, karate, some forms of taekwondo …

The meaning of KNOCKOUT is the act of knocking out : the condition of being knocked out. How to use knockout in a sentence.

If you describe someone or something as a knockout, you think that they are extremely attractive or impressive.

knockout noun [C] (COMPETITION) (US elimination tournament) a competition in which only the winners of each stage play in the next stage, until one competitor or team is the final winner:

knock•out (ˈnɒkˌaʊt) n. 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.

KNOCKOUT definition: an act or instance of knocking out. See examples of knockout used in a sentence.

a panel in a casing, can, or box, esp. 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.