- fail safe
- fail safeTo revert to a safe condition in the event of failure• • •Main Entry: ↑fail
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–adj.1. having a built-in safety device that is automatically activated to protect the operator from injury or its parts from damage, in case of power failure or malfunction of some part of the machine: »A fail-safe reel brake prevents accidental spilling of tape in case of power failure (Science News). The authority said that subway trains were equipped with a fail-safe device that halts the train automatically if the brakes fail (New York Times).
2. guaranteed no to fail; safe from failure; foolproof: »A master plan was worked out, beautifully turned and fail-safe on paper (Manchester Guardian Weekly).
–v.i.to stop or alter an operation automatically in case of some malfunction or power failure: »Those with gas central heating will have cursed the irony of a system which fails-safe when the electrical power supply is severed (Anthony Tucker).
–v.t.to make or cause to be fail-safe.╂[< Fail Safe]Fail Safe,a procedure of the U.S. Strategic Air Command in which a bomber may not proceed toward its target beyond a certain point until a final affirming order has been issued: »And even beyond Fail Safe point and all the way to bomb-drop point, the war order can be reversed and the aircraft called home (Time).
Useful english dictionary. 2012.