noun
regulation at-bats; required plate appearances
Baseball term for the minimum number of plate appearances a player needs to qualify for batting titles or rate statistics.
首位打者になるには規定打席に達している必要がある。
To become the batting champion, you must reach the required number of plate appearances.
打席 is a single plate appearance, while 規定打席 is the minimum total required for statistical qualification.
Compound of 規定 (regulation, prescribed) and 打席 (plate appearance).