From Longman Dictionary of Contemporary Englishcheckmatecheck‧mate /ˈtʃekmeɪt/ noun [countable, uncountable] 1 DGBthe position of the king (=most important piece) in chess at the end of the game, when it is being directly attacked and cannot escape2 a situation in which someone has been completely defeated —checkmate verb [transitive] The king is checkmated and the game is over.
Examples from the Corpus
checkmate• It was not a checkmate move.• If they succeed in cutting it, they will have achieved checkmate.• That is checkmate for his argument.Origin checkmate (1400-1500) Old French eschec mat, from Arabic shah mat, from Persian, “the king is left helpless” 