What is "perpetual check"

n. (context chess English) A draw forced by one player by putting the opponent's king in a potentially infinite series of checks.

In the game of chess, perpetual check is a situation in which one player can force a draw by an unending series of checks. Such a situation typically arises when the player who is checking cannot deliver checkmate, while failing to continue the series of checks gives the opponent at least a chance to win. A draw by perpetual check is no longer one of the rules of chess. However, such a situation will eventually result in a draw by either threefold repetition or the fifty-move rule, but usually players agree to a draw .

Perpetual check can also occur in other chess variants, although the rules relating to it may be different. For example, giving perpetual check is not allowed (an automatic loss for the giver) in both shogi and xiangqi.