at fault

at fault — adjective

1. being the person or thing that caused a problem, accident, or mistake to happen

1.adjectiveB2
Definition

being the person or thing that caused a problem, accident, or mistake to happen — and therefore deserving of blame

Example

The insurance report found that the truck driver was at fault for the crash.

be at fault for [something]

Emiko admitted she was at fault when the glass display broke during the event.

Common collocations
  • be at fault
  • find someone at fault
  • admit being at fault
  • the party at fault
  • at fault for the accident
Synonyms
  • responsible

    broader and more formal; can describe ongoing duties, not just one-off blame

  • to blame

    interchangeable with 'at fault' in most everyday contexts; slightly more direct

  • culpable

    formal and legalistic; implies moral or legal wrongdoing

  • in the wrong

    less formal; focuses on being mistaken rather than causing harm

Antonyms
  • blameless

    did nothing to cause the problem; free of any fault

  • in the clear

    informal; no longer suspected or blamed after an investigation

Grammar Patterns

be at fault

find [someone] at fault

be at fault for [something]

Usage Note

Almost always used after a linking verb (be, seem, appear) or verbs like find, consider, and deem. It is not used before a noun — you cannot say 'an at-fault driver' (use the hyphenated form 'at-fault' as an attributive adjective instead). In legal and insurance contexts it carries a formal, binding meaning about liability.

Common Mistakes

He was in fault for the broken window.
He was at fault for the broken window.
the fixed phrase uses 'at', never 'in'.
The court found the man guilty for the car accident.
The court found the man at fault for the car accident.
'guilty' is for criminal charges in a court of law; 'at fault' is for responsibility in accidents and everyday mistakes.

Synonym discussion

Sense: adjective/1

All four words point to blame, but they differ in register, scope, and tone. 'At fault' is the most natural choice for accidents, mistakes, and everyday mishaps — it names the source of a problem without strong moral condemnation. 'Responsible' is broader and more formal: a manager is responsible for the team (ongoing duty), but only at fault when something specific goes wrong. 'To blame' is the closest synonym in everyday speech and the two are often interchangeable, though 'to blame' feels slightly more direct and personal ('Who is to blame for this mess?'). 'Culpable' is the heavyweight — it belongs in legal and formal disciplinary settings and implies a serious moral or legal failing ('the board was found culpable of negligence'). 'In the wrong' is the softest of the group; it suggests being mistaken rather than causing harm and is common in personal disputes ('He finally admitted he was in the wrong'). Example contrast: The cyclist was at fault in the collision (neutral, factual); The CEO is responsible for the company's finances (ongoing duty); The manager was found culpable of fraud (legal/moral); I was in the wrong for shouting at her (personal admission).

responsible ↗to blame ↗culpable ↗in the wrong ↗

Etymology

LatinOld FrenchMiddle EnglishEnglish

The noun 'fault' entered English from Old French 'faute', meaning a lack, failing, or defect. That word traces back to the Latin verb 'fallere', meaning 'to deceive' or 'to fail'. The phrase 'at fault' first appeared in English in the 1500s as a hunting term — a hound that lost the scent trail was said to be 'at fault'. By the early 1600s, the meaning had broadened from a dog losing its way to a person being in the wrong or responsible for a mistake, which is the only surviving sense in everyday use today.

First known use

1607

1607, in the meaning defined at sense 2