fail

American  

[feyl] / feɪl /

verb (used without object)

1. to fall short of success or achievement in something expected, attempted, desired, or approved.

   The experiment failed because of poor planning.

2. to receive less than the passing grade or mark in an examination, class, or course of study.

   He failed in history.

3. to be or become deficient or lacking; be insufficient or absent; fall short.

   Our supplies failed.

4. to dwindle, pass, or die away.

   The flowers failed for lack of rain.

5. to lose strength or vigor; become weak.

   His health failed after the operation.

6. to become unable to meet or pay debts or business obligations; become insolvent or bankrupt.

7. (of a building member, structure, machine part, etc.) to break, bend, crush, or be otherwise destroyed or made useless because of an excessive load.

8. to stop functioning or operating.

   The electricity failed during the storm.

9. Slang.

   1. 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!

   2. to be embarrassingly incompetent, stupid, etc..

      She fails at life. I just failed at walking and fell on my face.

   3. to be bad or of inferior quality.

      The play is terrible—even the music fails.

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verb (used with object)

1. to be unsuccessful in the performance or completion of.

   He failed to do his duty.

2. (of some expected or usual resource) to prove of no use or help to.

   His friends failed him. Words failed her.

3. to receive less than a passing grade or mark in.

   He failed history.

4. 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

1. Slang.

   1. 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.

   2. the condition or quality resulting from having failed in this way.

      His online post is full of fail.

   3. a person who fails in this way.

2. Stock Exchange.

   1. a stockbroker's inability to deliver or receive security within the required time after sale or purchase.

   2. such an undelivered security.

3. Obsolete. failure as to performance, occurrence, etc.

interjection

1. Slang.

   1. (used to mock an embarrassing or humorous mistake, humiliating situation, etc., giving it an exaggerated importance).

      A tattoo that misspells your name? Fail!

   2. (used to indicate that something is bad or of inferior quality)

adjective

1. unsuccessful; failed.

   a totally fail policy.

2. Slang.

   1. of or noting an embarrassing or humorous mistake, humiliating situation, etc..

      the top 100 funniest fail photos on the internet.

   2. embarrassingly incompetent, stupid, etc.

      Why am I so fail?

   3. very bad or of inferior quality.

idioms

1. without fail, with certainty; positively.

   I will visit you tomorrow without fail.

fail ¹ British  

/ feɪl /

verb

1. to be unsuccessful in an attempt (at something or to do something)

2. (intr) to stop operating or working properly

   the steering failed suddenly

3. to judge or be judged as being below the officially accepted standard required for success in (a course, examination, etc)

4. (tr) to prove disappointing, undependable, or useless to (someone)

5. (tr) to neglect or be unable (to do something)

6. (intr) to prove partly or completely insufficient in quantity, duration, or extent

7. (intr) to weaken; fade away

8. (intr) to go bankrupt or become insolvent

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noun

1. a failure to attain the required standard, as in an examination

2. definitely; with certainty

fail ² British  

/ fel /

noun

1. a turf; sod

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fail More Idioms  

1. see without fail; words fail me.

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Other Word Forms

• unfailed
  adjective

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

In both cases, adipocytes fail to regulate energy normally, which can contribute to insulin resistance, type 2 diabetes, fatty liver disease, inflammation, and cardiovascular problems.

From Science Daily • May 8, 2026

“Most transformations succeed or fail because of people.”

From The Wall Street Journal • May 8, 2026

"I fail to understand why anybody... is serving people at five or six o’clock in the morning," he told the paper.

From Barron's • May 6, 2026

Note Liverpool's high defensive line while their attackers fail to apply pressure to Barcelona's defenders, giving them time to pick passes.

From BBC • May 4, 2026

Not only did the re-seeding fail by not generating much grass, it also created an environment where the natural growth that was occurring—the trees—were destroyed in the process.

From "Mountain of Fire" by Rebecca E. F. Barone

Related Words

• break
• close
• drop
• end
• finish