knocked out vs KO'd

knocked out and KO'd both are adjectives.

Word	Noun	Adjective	Verb	Adverb
knocked out	No	Yes	No	No
KO'd	No	Yes	No	No

As adjectives, knocked out and KO'd are synonyms defined as:

Other synonyms of knocked out include kayoed, out, stunned.

knocked out (adjective)	KO'd (adjective)
knocked unconscious by a heavy blow	knocked unconscious by a heavy blow