Sports A victory in boxing in which one's opponent is unable to rise from the canvas within a specified time after being knocked down or is judged too injured to continue.
Sports The act of winning a boxing match in this way: won the fight by a knockout.
Slang A strikingly attractive or impressive person or thing.
Capable of knocking out: a knockout punch.
Strikingly attractive or impressive.
Having a specific single gene removed from the genome by genetic manipulation: knockout mice used in an experiment.