fault

American  

[fawlt] / fɔlt /

noun

1. a defect or imperfection; flaw; failing.

   a fault in the brakes;

   a fault in one's character.

   Synonyms:

   shortcoming, frailty, blemish

   Antonyms:

   perfection, merit, strength, virtue

2. responsibility for failure or a wrongful act.

   It is my fault that we have not finished.

3. an error or mistake.

   a fault in addition.

4. a misdeed or transgression.

   to confess one's faults.

5. Sports. (in tennis, handball, etc.)

   1. a ball that when served does not land in the proper section of an opponent's court.

   2. a failure to serve the ball according to the rules, as from within a certain area.

6. Geology, Mining. a break in the continuity of a body of rock or of a vein, with dislocation along the plane of the fracture fault plane.

7. Manège. (of a horse jumping in a show) any of a number of improper executions in negotiating a jump, as a tick, knockdown, refusal, or run-out.

8. Electricity. a partial or total local failure in the insulation or continuity of a conductor or in the functioning of an electric system.

9. Hunting. a break in the line of scent; a losing of the scent; check.

10. Obsolete. lack; want.

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verb (used without object)

1. to commit a fault; blunder; err.

2. Geology. to undergo faulting.

verb (used with object)

1. Geology. to cause a fault in.

2. to find fault with, blame, or censure.

idioms

1. at fault,

   1. open to censure; blameworthy.

      to be at fault for a mistake.

   2. in a dilemma; puzzled.

      to be at fault as to where to go.

   3. (of hounds) unable to find the scent.

2. find fault, to seek and make known defects or flaws; complain; criticize.

   He constantly found fault with my behavior.

3. to a fault, to an extreme degree; excessively.

   She was generous to a fault.

fault British  

/ fɔːlt /

noun

1. an imperfection; failing or defect; flaw

2. a mistake or error

3. an offence; misdeed

4. responsibility for a mistake or misdeed; culpability

5. electronics a defect in a circuit, component, or line, such as a short circuit

6. geology a fracture in the earth's crust resulting in the relative displacement and loss of continuity of the rocks on either side of it

7. tennis squash badminton an invalid serve, such as one that lands outside a prescribed area

8. (in showjumping) a penalty mark given for failing to clear or refusing a fence, exceeding a time limit, etc

9. hunting an instance of the hounds losing the scent

10. deficiency; lack; want

11. 1. guilty of error; culpable

    2. perplexed

    3. (of hounds) having temporarily lost the scent

12. to seek out minor imperfections or errors (in); carp (at)

13. excessively

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verb

1. geology to undergo or cause to undergo a fault

2. (tr) to find a fault in, criticize, or blame

3. (intr) to commit a fault

fault Scientific  

/ fôlt /

1. A fracture in a rock formation along which there has been movement of the blocks of rock on either side of the plane of fracture. Faults are caused by plate-tectonic forces.

2. See more at normal fault reverse fault strike-slip fault thrust fault transform fault See Note at earthquake

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fault Cultural  

1. In geology, a place where sections of the crust of the Earth move relative to each other. (See earthquake and San Andreas fault.)

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fault More Idioms  

1. see at fault; find fault; to a fault.

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Usage

What does fault mean? A fault is a defect, flaw, or imperfection in something, as in LaShona found the fault in the code that prevented the website from working correctly. Fault is also responsibility for a failure or wrongful act, as in It was Jason’s fault that the puppy escaped because he left the front door open. A fault is also an error or mistake, such as a fault in a solution to a math problem. To fault someone is to blame them for an error, as in I can’t fault my sister for wanting to be like me. Fault is commonly used in the idioms at fault and find fault. Someone who is at fault is guilty or responsible for something and could be blamed. Someone who finds fault exposes the flaws of a person or the defects of a product. Example: It’s not my fault that the slippery dish fell out of my hands and broke.

Related Words

Fault, failing, foible, weakness, vice imply shortcomings or imperfections in a person. Fault is the common word used to refer to any of the average shortcomings of a person; when it is used, condemnation is not necessarily implied: A quick temper is her greatest fault. Foible, failing, weakness all tend to excuse the person referred to. Of these foible is the mildest, suggesting a weak point that is slight and often amusing, manifesting itself in eccentricity rather than in wrongdoing: the foibles of artists. Weakness suggests that the person in question is unable to control a particular impulse, and gives way to self-indulgence: a weakness for pretty women. Failing is closely akin to fault, except that it is particularly applied to humanity at large, suggesting common, often venial, shortcomings: Procrastination and making excuses are common failings. Vice (which may also apply to a sin in itself, apart from a person: the vice of gambling ) is the strongest term, and designates a habit that is truly detrimental or evil.

Closer Look

Bedrock, the solid rock just below the soil, is often cracked along surfaces known as planes. Cracks can extend up to hundreds of kilometers in length. When tensional and compressional stresses cause rocks separated by a crack to move past each other, the crack is known as a fault. Faults can be horizontal, vertical, or oblique. The movement can occur in the sudden jerks known as earthquakes. Normal faults, or tensional faults, occur when the rocks above the fault plane move down relative to the rocks below it, pulling the rocks apart. Where there is compression and folding, such as in mountainous regions, the rocks above the plane move upward relative to the rocks below the plane; these are called reverse faults. Strike-slip faults occur when shearing stress causes rocks on either side of the crack to slide parallel to the fault plane between them. Transform faults are strike-slip faults in which the crack is part of a boundary between two tectonic plates. A well-known example is the San Andreas Fault in California. Geologists use sightings of displaced outcroppings to infer the presence of faults, and they study faults to learn the history of the forces that have acted on rocks.

Discover More

Faults tend to occur near the edges of tectonic plates.

Other Word Forms

• postfault
  noun

Etymology

Origin of fault

First recorded in 1250–1300; Middle English faute, faulte, from Anglo-French, Middle French, from unattested Vulgar Latin fallita, noun use of feminine of unattested fallitus, for Latin falsus, past participle of fallere “to be wrong”

Explanation

A fault is an error caused by ignorance, bad judgment or inattention. If you're a passenger, it might be your fault that your friend missed the exit, if you were supposed to be watching for it, not sleeping. Fault can mean "blame" — as a noun or verb. If you say, "It's my fault," you accept the blame. Well, they can't fault you for telling the truth, at least. A fault can be a shortcoming — everyone has faults because no one is perfect — or a crack in the earth's crust, like the San Andreas Fault. In sports like tennis, a fault is an illegal hit of the ball, usually when it lands outside the playing area.

Example Sentences

In this case, an Old World hantavirus was at fault, not the Andes strain that’s responsible for the outbreak on the cruise ship.

From MarketWatch • May 8, 2026

Spirit had another recent problem that wasn’t its fault: the defective engines on the Airbus planes.

From Slate • May 5, 2026

The latter is “a pretty big fault but has been pretty quiet lately,” she said.

From Los Angeles Times • May 4, 2026

She said: "He died as he feared he would - having lost everything, through no fault of his own."

From BBC • May 4, 2026

The families would want me to tell the truth, somehow, about what had happened to their sons and how it was my fault that it happened.

From "The Brightwood Code" by Monica Hesse

Related Words

• blunder
• crime
• defect
• error
• failing
• flaw
• guilt
• indiscretion
• lapse
• liability
• misconduct
• miscue
• misdeed
• negligence
• offense
• omission
• oversight
• responsibility
• transgression
• weakness