What is a dead ball to you all?

For me a dead ball is one that is cracked so deep that it is not usable.
If the ball goes down the lane and does not knock over any pins but yet you hit the pocket.I would call that a dead ball.


Anyway besides losing the backend reaction,cracking,What are other signs of a "dead ball"?

Also if your just losing the backend reaction wouldn't a resurface of the coverstock bring it back from the dead?