fail–safe
/ˈfeɪlˌseɪf/
adjective
Britannica Dictionary definition of FAIL–SAFE
[more fail–safe; most fail–safe]
:
certain not to fail
-
Of course, no system is entirely fail-safe.
-
He was looking for a fail-safe source of money.
-
a fail-safe device/mechanism [=a device/mechanism that will not break]