fail-safe

American  

[feyl-seyf] / ˈfeɪlˌseɪf /

adjective

1. Electronics. pertaining to or noting a mechanism built into a system, as in an early warning system or a nuclear reactor, for insuring safety should the system fail to operate properly.

2. equipped with a secondary system that insures continued operation even if the primary system fails.

3. (sometimes initial capital letter) of, relating to, or designating a system of coded military controls in which bombers dispatched to a prearranged point as part of a standard operating procedure cannot advance farther without direct orders from a designated authority and cannot have the nuclear warheads they carry armed until they have passed their prearranged point.

4. guaranteed to work; totally reliable.

   a fail-safe recipe for a cheese soufflé.

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noun

1. (sometimes initial capital letter) the point beyond which the bombers cannot go without specific instruction; the fail-safe point.

2. something designed to work or function automatically to prevent breakdown of a mechanism, system, or the like.

verb (used with object)

fail-safed, fail-safing

1. to make fail-safe.

fail-safe British  

adjective

1. designed to return to a safe condition in the event of a failure or malfunction

2. (of a nuclear weapon) capable of being deactivated in the event of a failure or accident

3. unlikely to fail; foolproof

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verb

1. (intr) to return to a safe condition in the event of a failure or malfunction

Etymology

Origin of fail-safe

First recorded in 1945–50; apparently from verb phrase to fail safe(ly)

Example Sentences

Though Mr Gove stressed that the Section 35 provision must remain a "fail safe power" that is "used sparingly".

From BBC • May 17, 2025

"It is important because there is no fail safe," Vrabel said.

From Fox News • Aug. 26, 2021

It’s up to the I-T guys at both the club and league to make sure that everything works - and that they have a fail safe.

From Washington Times • Apr. 14, 2020

The bill also instructs Chao, within two years, to require “safety assessment certifications” that demonstrate driverless vehicles “are likely to . . . function as intended and contain fail safe features.”

From Washington Post • Sep. 5, 2017

Since everything aboard a starship is designed to fail safe, they were, of course, in normal space.

From Subspace Survivors by Dongen, H. R. van