checkmate

     "Checkmate" means the end of a chess game. It is the chess equivalent of  "I win!"  The object of the chess game is to capture ( some people use the word kill ) the opponent's king. All of the other pieces on the board are attempting to protect their own king, and attack the enemy king. When the enemy king is surrounded, he is in "check". When he is surrounded with no escape, the opponent has been "checkmated", and the game is over. Some people signify this by knocking over the king ( their own "checkmated" king ), as an admission of defeat. To reach out and knock over someone else's king is considered quite nasty. The checkmated opponent will want to examine the board for any possible move left open. The opponent may find a move you didn't notice, and might still win the game. So play nice.