Well, in boxing, the fight is over when one of the fighters is knocked unconscious. From
Wiki: "...the referee begins counting until the fighter returns to his or her
feet and can continue. Should the referee count to ten, then the
knocked-down boxer is ruled "knocked out" (whether unconscious or not)
and the other boxer is ruled the winner by knockout (KO)."
This gives us the useful phrase "down for the count," which can be used outside the boxing ring as well.
So, I'm guessing it merely means defeated. But perhaps the movie you are watching depicts a very brutal society, one in which a violent death is treated as lightly as a defeat on the playing field. In that case it would mean both defeated and dead. :)