Fail-safe (adjective)
definition:
eliminating danger by compensating automatically for a failure or malfunction
example:
"a fail-safe device in a nuclear weapon to deactivate it automatically in the event of accident"
Fail-safe (adjective)
definition:
guaranteed not to fail
example:
"a fail-safe recipe for cheese souffle"
Fail-safe (noun)
definition:
a mechanism capable of returning to a safe state in case there is a failure or malfunction