Synonyms of fail safe

Noun

1. fail-safe, mechanism

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

Adjective

1. fail-safe, secure (vs. insecure)

usage: guaranteed not to fail; "a fail-safe recipe for cheese souffle"

2. fail-safe, safe (vs. dangerous)

usage: 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"