A blow that renders an opponent unconscious in a boxing match. The boxer delivered a powerful punch that resulted in a knockout in the third round.
A person or thing that is overwhelmingly impressive or attractive. She walked into the room wearing a stunning dress and was an absolute knockout.
A competition in which the loser of each match is eliminated. The team advanced to the knockout stage of the tournament after winning all their group matches.
Genetics: an organism in which a specific gene has been inactivated or removed. The researchers bred a knockout mouse to investigate the role of that gene in development.