Baseball term for a substitute batter. Also used figuratively for a person who steps in to replace someone in a task or role.
In the bottom of the ninth, a veteran player was sent in as a pinch hitter.
彼は交渉の場で代打者として呼ばれた。
He was called in as a pinch hitter at the negotiation.
Compound of 代 (substitute) + 打 (hit) + 者 (person).