fail-safe

[ feyl-seyf ]

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.

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-saf·ing.

1. to make fail-safe.

fail-safe

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

verb

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

Word History and Origins

Origin of fail-safe¹

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

Example Sentences

And because airplanes are packed with fail-safes, there are times when a flight with a malfunctioning system can safely proceed simply by relying on one or more backups instead.

From New York Times

This is a fail-safe scenario but the converse "wrong side" failures -- when the signal goes from red to green -- are much more hazardous.

From Science Daily

However, discussions of fall-backs and fail-safes have not been welcome in the Wales camp while the possibility of automatic qualification remains.

From BBC

"These memory immune cells with latent suppressive properties act as a fail-safe mechanism in addition to the protection from traditional memory suppressive T cells."

From Science Daily

He made his money through Green Hill Software, a company he founded in 1982 that develops fail-safe operating systems and programming tools for commercial customers.

From Los Angeles Times