What is the meaning of Fail-safe?

That does not cause undue damage in the event of failure.

Designed to shut off for safety if an emergency occurs.

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

To compensate automatically, in the event of a failure.

To make a device or mechanism fail-safe, or to add a fail-safe device or mechanism to an existing system.

Source: wiktionary.org