Fail-safe

Fail-safe or fail-secure describes a device or feature which, in the event of failure, responds in a way that will cause no harm or at least a minimum of harm to other devices or danger to personnel. Fail-safe components of a system are distinguished from fail-secure components in that, in the former, component failure allows but does not cause or invite a certain improper system behavior, whereas in the latter, component failure does not allow a certain improper system behavior, although some proper behaviors are impeded.

Source: Wikipedia - Fail-safe