ENGLISH
REFERENCE

fail

v. · n.
US //ˈfeɪɫ// UK //fˈeɪl// fail
  1. 1 to be unsuccessful (v.)
    A2 Elementary

    to not succeed in achieving a goal or doing what you tried to do.

    to be unsuccessful in an endeavour or to fall short of a required standard.

    Example

    He failed to finish the race because he hurt his leg halfway through.

    Example

    Despite their significant investment in research and development, the startup failed to capture a viable share of the competitive smartphone market.
  2. 2 academic grading (v.)
    A2 Elementary

    to not pass a test or an exam; also, when a teacher gives you a non-passing grade.

    to receive or assign a non-passing grade in an academic context. Ambitransitive use.

    Example

    I am worried that I might fail my driving test for the second time.

    Example

    The professor warned that he would fail any student who was caught plagiarising their final thesis.
    • flunk
Show 4 more sensesShow fewer
  1. 3 to stop working (v.)
    B1 Intermediate

    when a machine, a part of the body, or a system stops working correctly.

    to cease functioning properly or to break down, often used of mechanical systems or biological organs.

    Example

    The car's brakes failed while he was driving down the steep hill.

    Example

    The backup generators failed during the storm, leaving the entire hospital without power for several critical hours.
  2. 4 to disappoint or let down (v.)
    B2 Upper Intermediate

    to not be there for someone when they need you, or to disappoint them.

    to prove deficient or insufficient in a time of need; to let someone down or desert them.

    Example

    I needed my friend's help, but she failed me when things got difficult.

    Example

    Words failed him as he stood before the crowd, unable to express the depth of his gratitude for their support.
  3. 5 an unsuccessful result (n.)
    B1 Intermediate

    a result that is not a pass, or a situation that did not go well.

    an instance of failure, particularly an academic grade that is not a pass.

    Example

    He was very upset when he saw a fail on his report card.

    Example

    The inspector recorded a fail for the building's safety systems, citing several blocked emergency exits.
  4. 6 an embarrassing mistake (n.)
    B2 Upper Intermediate Informal Slang

    a funny or embarrassing mistake, often shown in videos or photos.

    a humiliating or ridiculous mistake or failure, often used in digital contexts to mock an error.

    Example

    The video of the cat missing the jump was a total fail.

    Example

    The marketing campaign was an absolute fail, as the slogan was accidentally translated into something offensive.
Etymology 1

Inherited from Middle English failen, borrowed from Old French falir, from Vulgar Latin fallire, alteration of Latin fallere (“to deceive, disappoint”), from Proto-Indo-European bʰāl- (“to lie, deceive”) or Proto-Indo-European *(s)gʷʰh₂el- (“to stumble”). Compare Alemannic German fääle (“to lack”), Cimbrian béelan, véelan (“to fail”), veln (“to be absent, missing”), Dutch falen, feilen (“to fail, miss”), German fallieren, fehlen (“to fail, miss, lack”), Danish fejle (“to fail, err”), Swedish fallera (“to fail, break, malfunction”), Spanish fallar (“to fail, miss”).

Etymology 2

Unknown. Compare Scottish Gaelic fàl (“hedge”), Scots faill (“turf”). Attested from the 16th century.

Word family
Idioms3 entries

© 2026 English Reference