fail
Americanverb (used without object)
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to fall short of success or achievement in something expected, attempted, desired, or approved.
The experiment failed because of poor planning.
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to receive less than the passing grade or mark in an examination, class, or course of study.
He failed in history.
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to be or become deficient or lacking; be insufficient or absent; fall short.
Our supplies failed.
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to dwindle, pass, or die away.
The flowers failed for lack of rain.
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to lose strength or vigor; become weak.
His health failed after the operation.
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to become unable to meet or pay debts or business obligations; become insolvent or bankrupt.
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(of a building member, structure, machine part, etc.) to break, bend, crush, or be otherwise destroyed or made useless because of an excessive load.
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to stop functioning or operating.
The electricity failed during the storm.
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Slang.
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to make an embarrassing or humorous mistake, be in a humiliating situation, etc., and be subject to ridicule.
Showed up late to the wedding? You fail!
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to be embarrassingly incompetent, stupid, etc..
She fails at life. I just failed at walking and fell on my face.
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to be bad or of inferior quality.
The play is terrible—even the music fails.
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verb (used with object)
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to be unsuccessful in the performance or completion of.
He failed to do his duty.
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(of some expected or usual resource) to prove of no use or help to.
His friends failed him. Words failed her.
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to receive less than a passing grade or mark in.
He failed history.
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to declare (a person) unsuccessful in a test, course of study, etc.; give less than a passing grade to.
The professor failed him in history.
noun
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Slang.
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an embarrassing or humorous mistake, humiliating situation, etc., that is subject to ridicule and given an exaggerated importance.
Their app update is a massive fail.
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the condition or quality resulting from having failed in this way.
His online post is full of fail.
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a person who fails in this way.
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Stock Exchange.
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a stockbroker's inability to deliver or receive security within the required time after sale or purchase.
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such an undelivered security.
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Obsolete. failure as to performance, occurrence, etc.
interjection
adjective
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unsuccessful; failed.
a totally fail policy.
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Slang.
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of or noting an embarrassing or humorous mistake, humiliating situation, etc..
the top 100 funniest fail photos on the internet.
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embarrassingly incompetent, stupid, etc.
Why am I so fail?
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very bad or of inferior quality.
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idioms
verb
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to be unsuccessful in an attempt (at something or to do something)
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(intr) to stop operating or working properly
the steering failed suddenly
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to judge or be judged as being below the officially accepted standard required for success in (a course, examination, etc)
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(tr) to prove disappointing, undependable, or useless to (someone)
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(tr) to neglect or be unable (to do something)
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(intr) to prove partly or completely insufficient in quantity, duration, or extent
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(intr) to weaken; fade away
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(intr) to go bankrupt or become insolvent
noun
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a failure to attain the required standard, as in an examination
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definitely; with certainty
noun
Other Word Forms
Derived Forms
Conjugated Forms
Present
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have failedperfect
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has failedperfect 3rd person singular
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have been failingperfect progressive
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am failingprogressive 1st person singular
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has been failingperfect progressive 3rd person singular
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failssingular 3rd person
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failingparticiple
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are failingprogressive
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is failingprogressive 3rd person singular
Past
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had failedperfect
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were failingprogressive plural
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was failingprogressive singular
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had been failingperfect progressive
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failedparticiple
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failedsimple
Future
Etymology
Origin of fail
First recorded in 1175–1225; Middle English failen, from Anglo-French, Old French faillir, from unattested Vulgar Latin fallīre, for Latin fallere “to disappoint, deceive”
Explanation
The verb fail describes something that stops working, like brakes in a car that fail, or is found to be unacceptable, like restaurants that fail their inspection for cleanliness. The verb fail comes from the Old French word faillir, meaning “be lacking,” “miss,” or “not succeed.” You can fail an exam, which means you didn't get at least a minimum number of points to pass. You can fail to live up to your potential, meaning you aren't able to meet expectations. When businesses fail, it means financial problems force them to close.
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.
"The policy of continuously strengthening the country's self-defensive nuclear deterrent, as set out by the nation's leader, is an irreversible course that must be implemented without fail," she added.
From Barron's • Jun. 7, 2026
Such errors have led to the faulty identification of “longevity zones,” areas where supposedly everyone lives longer due to lifestyle or location—but where subsequent studies fail to substantiate the claims.
From The Wall Street Journal • Jun. 5, 2026
One parent says she believes "students were set up to fail".
From BBC • Jun. 5, 2026
The Santa Barbara Botanic Garden has seeds for all of the rare plants in the burn area, a sort of fail safe if they need help recovering.
From Los Angeles Times • Jun. 5, 2026
“Your punishment, if you fail, will be toadification. Should you survive, that is.”
From "Witchlings" by Claribel A. Ortega
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.
