Knockout, or simply knock, is a winning criterium of many ringsports, such as boxing, kickboxing, muay thai and others. A knocked participant is either unconcious or sufficiently unbalanced and confused to be unable to continue the fight for the time being.
Since knock is not always possible to achieve, other winning criteria are usually employed as well.
Repeted blows to the head is known to produce damage to the cerebrum, such as concussion and in extreme cases internal bleeding within the brain. Because of this, many physicians advise against knockout sports.