An The cube in match play when it has no utility to a player who has the option of doubling. For example, the cube is dead if its value exceeds the number of points needed to win the match.

This is a term used in backgammon match play when the doubling cube is not further used because the value of the cube is enough for the player to win the match. It is sometimes easier to double an opponent when you know the cube will be dead if it is accepted because you know it cannot be given back to you to double the stakes yet again.

This happens when the doubling cube has no meaning and value in re-doubling the game.  If a game is played to three points and the cube doubled to 4, there is no meaning of re-doubling it.