noun
regular pitcher; starting pitcher
Baseball term for the pitcher who is the team's regular starter, as opposed to a relief pitcher or substitute.
彼はチームの正投手として、開幕戦に先発した。
As the team's regular pitcher, he started the opening game.
リリーフ投手 is a relief pitcher who enters the game later, contrasting with the regular starter role of 正投手.
Compound of 正 (regular, main) and 投手 (pitcher). A straightforward baseball term.