fail-safe

Short definition from Wiktionary

Adjective

1. 1
   That does not cause undue damage in the event of failure.
2. 2
   Designed to shut off for safety if an emergency occurs.

Noun

1. 1
   A device, mechanism or measure designed to make something fail-safe.

Verb

1. 1
   To compensate automatically, in the event of a failure.
2. 2
   To make a device or mechanism fail-safe, or to add a fail-safe device or mechanism to an existing system.
3. 3
   Alternative form of fail-safe (verb with differing inflections)