fail-safe
UK: ˈfeɪlseɪf | US: ˈfeɪlseɪf
adj. designed to stop or revert to a safe state if a system fails
n. a mechanism or feature ensuring safety in case of failure
The term "fail-safe" emerged in the early 20th century, combining "fail" (from Old French faillir, meaning "to be lacking") and "safe" (from Old French sauf, meaning "unharmed"). It originally described engineering systems (e.g., brakes, nuclear reactors) designed to default to a harmless state upon failure. The logic reflects a direct cause-effect relationship: if something fails, it must still remain safe.
The elevator has a fail-safe mechanism to prevent free-falling.
Engineers prioritized fail-safe designs in the aircraft's control system.
The software includes a fail-safe to backup data during crashes.
Nuclear reactors rely on fail-safe protocols to avoid meltdowns.
Always test the fail-safe feature before deploying the device.