The Collaborative International Dictionary of English v.0.48:
KO \KO\ v. t. [imp. & p. p. KO'd; p. pr. & vb. n. KO'ing.] To knock out; to deliver a blow that renders (the opponent) unconscious; -- used especially in boxing. [acronym] Syn: knockout. [WordNet 1.5]The Collaborative International Dictionary of English v.0.48:
KO'd \KO'd\ adj. [from KO, v. t.] rendered unconscious, usually by a blow. Syn: knocked out(predicate), kayoed, out(predicate), stunned. [WordNet 1.5]