Fail-safe

adj.resilient, capableprofessional

What it means

Designed to enter or preserve a safe condition when a component or process fails.

Reach for it when praising a safety design whose failure behavior has been deliberately controlled

A fail-safe latch releases the gate if the motor loses power.

everyday
error-proof
a process is arranged to prevent common user mistakes
not when Error-proof overpromises when hardware failure remains possible.
everyday
foolproof
simplicity makes misuse unlikely in casual explanation
not when Foolproof can sound absolute and dismissive of unusual failure modes.
professional
fault-tolerant
continued operation despite a component failure is the requirement
not when Fault-tolerant equipment may keep running without moving into the safest state.
professional
interlocked
one action must be blocked until a safe condition exists
not when An interlock addresses a defined sequence, not every possible failure.
professional
redundant
backup components provide another route after failure
not when Redundancy improves resilience but does not by itself guarantee safe failure behavior.
professional
safe-by-default
the ordinary fallback state should minimize harm
not when Safe-by-default describes a design principle rather than a tested mechanism.
formal
self-protecting
the system automatically prevents damage to itself
not when Self-protection may safeguard the machine while leaving users exposed.

fail-safe mechanism
The boiler's fail-safe mechanism shuts the fuel valve automatically.
fail-safe mode
The controller enters fail-safe mode when sensor readings conflict.
fail-safe brake
A fail-safe brake holds the lift during a power loss.
fail-safe design
The review documented how each fail-safe design responds to a broken cable.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.