noun
regulation baseball; hardball
Refers to baseball played with a hard ball, as opposed to 軟式野球 (rubber-ball baseball). Used in contexts like school clubs and official competitions.
See also: 軟式野球
高校から硬式野球部に入った。
I joined the hardball baseball club in high school.
硬式
The hardness of the ball differs between regulation baseball and rubber-ball baseball.