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1. noun, slang An initialism for "knockout," a victory in boxing in which one's opponent is knocked to the mat and unable to rise within a specific amount of time. He's strong, but he lacks stamina. He'll try to win with a KO in the early rounds, but if you can avoid his punches, you'll be able to tire him out. She's got more KOs than any other boxer in history.
2. verb, slang To achieve a victory by knockout. He KOed his opponent in just 45 seconds. Don't worry about KOing him—focus on your jabs, blocks, and footwork.
3. verb, slang To render someone unconscious. Be careful drinking that stuff. It'll KO you! Sorry for not calling you back. I sat down after getting home from that hike and was instantly KOed. He KOed Jeff with a single punch to the head.
slang Rendered asleep or unconscious, as from drugs, alcohol, fatigue, or a physical blow. Jim started drinking shots whiskey with his beers and was KOed by 11 PM. Sorry for not calling you back. I lay down after we got home from the hike and was instantly KOed. Just one punch to Jim's head left him KOed on the sidewalk.
See also: KO
KOand kayo (ˈkeˈo)
1. n. a knockout. (The abbreviation is an initialism. Boxing.) It was a quick KO, and Wilbur was the new champ.
2. tv. to knock someone out. (see also KOed. Boxing.) Wilbur planned to KO Wallace in the third round.
1. mod. knocked out. (Initialism. Originally from boxing.) Wilbur was KOed and got a cut over his eye.
2. mod. alcohol or drug intoxicated. (Initialism.) Both guys were KOed and spent the night.
See also: KO