technical knockout

noun, Boxing.
1.
the termination of a bout by the referee when it is the judgment of the attending physician, a boxer's seconds, or the referee that a boxer cannot continue fighting without sustaining severe or disabling injury.
Abbreviation: TKO, T.K.O.
Origin
1945-50
British Dictionary definitions for technical knockout

technical knockout

noun
1.
(boxing) a judgment of a knockout given when a boxer is in the referee's opinion too badly beaten to continue without risk of serious injury