checkmate

nouns

complete victory
checkmate
is a type of (narrower)
a successful ending of a struggle or contest
"a narrow victory"; "the general always gets credit for his army's victory"; "clinched a victory"; "convincing victory"; "the agreement was a triumph for common sense"
triumph, victory
a chess move constituting an inescapable and indefensible attack on the opponent's king
checkmate, mate

verbs

place an opponent's king under an attack from which it cannot escape and thus ending the game
"Kasparov checkmated his opponent after only a few moves"
checkmate, mate