[ feyl-seyf ]
/ ˈfeɪlˌseɪf /
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.
equipped with a secondary system that insures continued operation even if the primary system fails.
(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.
guaranteed to work; totally reliable: a fail-safe recipe for a cheese soufflé.
(sometimes initial capital letter) the point beyond which the bombers cannot go without specific instruction; the fail-safe point.
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.
to make fail-safe.
Origin of fail-safe
First recorded in 1945–50; apparently from verb phrase to fail safe(ly)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for failsafe
designed to return to a safe condition in the event of a failure or malfunction
(of a nuclear weapon) capable of being deactivated in the event of a failure or accident
unlikely to fail; foolproof
(intr) to return to a safe condition in the event of a failure or malfunction
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for failsafe
Online Etymology Dictionary, © 2010 Douglas Harper