fail-safe

nouns

a mechanism capable of returning to a safe state in case there is a failure or malfunction

fail-safe

is a type of (narrower)

device consisting of a piece of machinery; has moving parts that perform some function

guaranteed not to fail

"a fail-safe recipe for cheese souffle"

fail-safe

is similar to

free from danger or risk

"secure from harm"; "his fortune was secure"; "made a secure place for himself in his field"

eliminating danger by compensating automatically for a failure or malfunction

"a fail-safe device in a nuclear weapon to deactivate it automatically in the event of accident"

fail-safe

is similar to

free from danger or the risk of harm

"a safe trip"; "you will be safe here"; "a safe place"; "a safe bet"