[verb] [T] he/she/it KO's, KO'ing, past KO'd [informal] - to knock out (= make unconscious), esp. in boxingAmazing! We've just seen the world's number one boxer KO'd in the first round! [T](figurative) That flu really KO'd me (= made me very weak) for a while. [T]
KO
Meaning of KO in English
Cambridge English vocab. Кембриджский английский словарь. 2012