to make someone lose consciousness by hitting them
He managed to knock his opponent out in the final round.
彼は最後のラウンドで対戦相手をノックアウトすることに成功した。
to eliminate someone from a competition so they cannot continue
The team was knocked out of the tournament after losing the last match.
そのチームは最後の試合に負けた後、トーナメントから脱落した。