KO

KO is a common abbreviation used primarily in combat sports like boxing, mixed martial arts (MMA), and kickboxing. A KO occurs when a fighter is rendered unconscious or unable to continue after being struck, leading to an immediate victory for their opponent.

People have used KO in competitive fighting for over a century, and it is widely recognized in both professional and amateur sports. Beyond combat sports, "KO" is also used in video games, especially in fighting games like Street Fighter and Mortal Kombat, where knocking out an opponent is often the objective.

Outside of sports, "KO" has entered everyday slang to describe anything that leaves someone physically or mentally drained. People might say they were "KO'd" after an exhausting workout, a long day, or even a potent beverage. People also use the term metaphorically in debates or arguments, where a strong counterpoint is said to "KO" the opposing argument.