1) The termination of an aversive stimulus by a response. A reduction in the magnitude of an aversive stimulus by a response is sometimes called partial or fractional escape.

2) Any behaviour that terminates a negative reinforcer.

3) The term escape describes a relation between a performance and an aversive stimulus in which the performance terminates the aversive stimulus. Escape is to be contrasted with avoidance, where the aversive stimulus does not occur at all as long as the avoidance performance continues to postpone it.