expression, godan verb (-su)
defeat one's opponent; beat the other party
A straightforward phrase for winning against someone in a contest, argument, or fight. The verb 負かす is a transitive godan verb meaning 'to defeat'.
彼は将棋で相手を負かした。
He defeated his opponent in shogi.
議論で相手を負かすのは難しい。
It's hard to beat your opponent in an argument.