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:
Wartsila said client confidentiality prevented it answering questions on why fail-safe monitoring equipment was not fitted on Glen Sannox, or who had access to its service notices.
From BBC ● Sep. 8, 2026
He said the boats went “dead in the water” as an automatic fail-safe, which prevented them from causing damage or injury.
From The Wall Street Journal ● Nov. 27, 2025
Congress created the Insurrection Act as a fail-safe in response to armed mobs attacking their neighbors and organized militias seeking to overthrow elected officials.
From Los Angeles Times ● Oct. 16, 2025
Level 4 automated vehicles, which this research was based on, are capable of automatically starting fail-safe and fail-operational protocols.
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
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 ● Jun. 19, 2024
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
It needs fail-safes that make it easier for factories to restart after being shut.
From Seattle Times ● Oct. 17, 2021
Fortunately, though, the new generation of submarines are built with so many levels of redundancy and fail-safes, the chances of anything bad happening are remote.
From Scientific American ● Feb. 12, 2018
“One of my mom’s fail-safes, just in case it has to be destroyed in a hurry.”
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.
