fail-safe
Americanadjective
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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.
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equipped with a secondary system that insures continued operation even if the primary system fails.
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(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.
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guaranteed to work; totally reliable.
a fail-safe recipe for a cheese soufflé.
noun
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(sometimes initial capital letter) the point beyond which the bombers cannot go without specific instruction; the fail-safe point.
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something designed to work or function automatically to prevent breakdown of a mechanism, system, or the like.
verb (used with object)
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fail-safes,
present (3rd person singular)
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fail-safed,
past participle, past
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fail-safing
present participle
adjective
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designed to return to a safe condition in the event of a failure or malfunction
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(of a nuclear weapon) capable of being deactivated in the event of a failure or accident
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unlikely to fail; foolproof
verb
Other Word Forms
Inflected Forms
Participles
Conjugated Forms
Present
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fail-safesimple
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fail-safessimple
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have fail-safedperfect
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has fail-safedperfect
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am fail-safingprogressive
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are fail-safingprogressive
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is fail-safingprogressive
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have been fail-safingperfect progressive
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has been fail-safingperfect progressive
Past
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fail-safedsimple
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had fail-safedperfect
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was fail-safingprogressive
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were fail-safingprogressive
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had been fail-safingperfect progressive
Future
Etymology
Origin of fail-safe
First recorded in 1945–50; apparently from verb phrase to fail safe(ly)
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Those recorded cues act as a fail-safe against technical malfunctions during the broadcast, though the orchestra aims to play everything live.
From Los Angeles Times ● Mar. 13, 2026
As a key oil producer, Saudi Arabia is relied upon to surge output and stabilize markets during crises, but any physical degradation of its export capacity neuters this critical fail-safe.
From The Wall Street Journal ● Mar. 2, 2026
The boats had rejected their inputs and automatically idled as a fail-safe, making them “dead” in the water.
From The Wall Street Journal ● Nov. 27, 2025
One significant solution implemented as a fail-safe for Level 4 automated vehicles is the concept of remote driving.
From Science Daily ● Nov. 21, 2024
Encoding provided a measure of security but was not fail-safe.
From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau
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 ● Nov. 20, 2023
“There are all sorts of fail-safes built into the system to avoid falsely accusing somebody of something,” Scollay said as the sport began the wait for the second result and Medina Spirit headed for Pimlico.
From Washington Post ● May 10, 2021
The local election board reported a simpler story: A new worker had incorrectly trashed the ballots, and its fail-safes had quickly identified the problem.
From New York Times ● Sep. 30, 2020
The company typically uses two or even three separate components as fail-safes for crucial tasks to reduce the possibility of a disastrous failure.
From Seattle Times ● Mar. 26, 2019
“Only the person who activated the STM can use it again. My mom has fail-safes against everything.”
From "The First State of Being" by Erin Entrada Kelly
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
