also: ゲーム・セット
noun
game, set and match; end of the game; end of the match
Wasei-eigo used in sports contexts to announce the conclusion of a game or match; also used figuratively to mean something is finished or decided.
wasei-eigo (Japanese-coined English), from game set
審判が「ゲームセット」と宣言した。
The referee declared 'game, set and match'.
これでゲームセットだ。
That's the end of the game.
A more formal, native Japanese term for the end of a match, used in official announcements.
Wasei-eigo from English 'game set', likely a shortening of 'game, set and match'.