also: かんぜんしあい
noun
Baseball term: a game in which no opposing player reaches base.
彼はプロ野球で完全試合を達成した。
He pitched a perfect game in professional baseball.
A no-hitter allows walks or errors; a 完全試合 is stricter, with no baserunners at all.
Compound of 完全 (perfect) and 試合 (game/match), directly calquing the English baseball term 'perfect game'.