check ‧ mate /ˈtʃekmeɪt/ BrE AmE noun [uncountable and countable]
[ Date: 1400-1500 ; Language: Old French ; Origin: eschec mat , from Arabic shah mat , from Persian , 'the king is left helpless' ]
1 . the position of the ↑ king (=most important piece) in ↑ chess at the end of the game, when it is being directly attacked and cannot escape
2 . a situation in which someone has been completely defeated
—checkmate verb [transitive] :
The king is checkmated and the game is over.