noun
triple three; 30+ HR, 30+ SB, .300+ AVG season
Baseball term for a season with a .300+ batting average, 30+ home runs, and 30+ stolen bases. Wasei-eigo from English 'triple three'.
wasei-eigo (Japanese-coined English), from triple three
彼は今シーズン、トリプルスリーを達成した。
He achieved a triple three this season.
Variant with interpunct, also seen in Japanese sources.
Wasei-eigo from English 'triple three', referring to the three statistical milestones in baseball.