Checkmate
Etymology
From Persian "shāh māt," passing through Arabic and Old French "eschec mat." "Māt" means "helpless" or "defeated," so the phrase is closer to "the king is helpless" than the popular mistranslation "the king is dead." It now marks any decisive, unanswerable move.
noun · /CHEK-mayt/
A final position from which an opponent has no escape, ending the game in defeat.
What it names
The moment a situation becomes inescapable — not just losing, but having no move left at all.
Example
Once the internal emails were made public, the regulators had him in checkmate.
Related idea
A checkmate ends the game in a loss, whereas a stalemate ends it in a draw with no winner at all.