Checkmate (noun)

1. A situation in the game of chess in which a player"s king is in a position to be captured (threatened with "check") and there is no way to move the king out of capture (mate).
2. An action or move that leads to a decisive defeat or defeat of a master plan.

Origin:

From the persian shah mat, meaning "the king is defeated", it has been used in western chess since the 15th century.

Examples:

1. I can"t believe I didn"t see that move coming, checkmate.
2. The company"s new strategy was supposed to guarantee success, but the competition"s counter-move proved to be a checkmate.
3. The chess grandmaster was so focused on winning, he didn't see the checkmate coming.
4. He thought he had the upper hand, but he was caught off guard by the checkmate move.
5. The game was intense, but in the end, it was checkmate for the red team.