noun
substitute player; substitution
Sports term for a player who replaces another during a game, or the act of substitution itself.
彼は交代選手として試合に出た。
He entered the game as a substitute player.
監督は交代選手をベンチから呼んだ。
The manager called a substitute from the bench.
Compound of 交代 (こうたい, 'alternation, substitution') and 選手 (せんしゅ, 'player, athlete').