noun
three-pitch strikeout
Baseball term for a strikeout achieved with exactly three pitches, each a strike.
彼は三球三振に抑えられた。
He was struck out on three pitches.
先発投手は初回に三球三振を奪った。
The starting pitcher got a three-pitch strikeout in the first inning.
三振 is a general strikeout, while 三球三振 specifies that the strikeout occurred on exactly three pitches.
Compound of 三球 (three pitches) and 三振 (three strikes, i.e., strikeout).