at fault

WordReference Random House Learner's Dictionary of American English © 2026

fault /fɔlt/  n. [countable]

1. a defect or imperfection;
   flaw;
   failing:
   His only fault is that he lacks ambition.
2. responsibility for failure or a wrongful act:
   [usually: singular] Whose fault was it?
3. an error or mistake;
   misdeed:
   a fault in addition.
4. Geology, Mining a break or crack in the continuity of a body of rock, or of the earth's surface:
   huge faults in southern California.

v. [~ + object)]

5. to accuse of error, misdeed, wrong, etc.;
   criticize;
   blame:
   The boss can't fault you on inaccuracy.

Idioms

6. Idioms at fault, in the wrong;
   deserving blame:
   She was at fault for lying.
7. Idioms find fault, [ find + ~ (+ with + obj)] to complain or be critical:
   always found fault with him no matter what he did.
8. Idioms to a fault, to an extreme degree;
   greatly;
   excessively:
   She was generous to a fault.

fault•less, adj. 
fault•less•ly, adv. 

WordReference Random House Unabridged Dictionary of American English © 2026

fault  (fôlt), n. 

1. a defect or imperfection;
   flaw;
   failing:
   a fault in the brakes; a fault in one's character.
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. Sport (in tennis, handball, etc.)
   • a ball that when served does not land in the proper section of an opponent's court.
   • 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. Sport [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. Sport [Hunting.] a break in the line of scent;
   a losing of the scent;
   check.
10. [Obs.] lack;
    want.
11. Idioms at fault:
    • open to censure;
      blameworthy:
      to be at fault for a mistake.
    • in a dilemma;
      puzzled:
      to be at fault as to where to go.
    • (of hounds) unable to find the scent.
12. Idioms find fault, to seek and make known defects or flaws;
    complain;
    criticize:
    He constantly found fault with my behavior.
13. Idioms to a fault, to an extreme degree;
    excessively:
    She was generous to a fault.

v.i. 

14. to commit a fault;
    blunder;
    err.
15. Geology to undergo faulting.

v.t. 

16. Geology to cause a fault in.
17. to find fault with, blame, or censure.

• Vulgar Latin *fallita, noun, nominal use of feminine of *fallitus, for Latin falsus, past participle of fallere to be wrong
• Anglo-French, Middle French
• Middle English faute 1250–1300

Synonyms

• 1. blemish; frailty, shortcoming.
  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:
  Of his many faults the greatest is vanity.
  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.

Antonyms

• 1. virtue, strength, merit.

Collins Concise English Dictionary © HarperCollins Publishers::

fault / 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. a defect in a circuit, component, or line, such as a short circuit
6. 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. 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. at fault ⇒ guilty of error; culpable
10. find fault ⇒ to seek out minor imperfections or errors (in); carp (at)
11. to a fault ⇒ excessively

verb

1. to undergo or cause to undergo a fault
2. (transitive) to find a fault in, criticize, or blame
3. (intransitive) to commit a fault

Etymology: 13th Century: from Old French faute, from Vulgar Latin fallita (unattested), ultimately from Latin fallere to fail