fault
n. C / Un. a mistake or a weakness in someone or something. It is also the responsibility for a bad situation or an accident.
n. a defect or imperfection in a person's character or a physical object; also, the responsibility for a failure or error. In its geological sense, it refers to a fracture in the Earth's crust.
The accident was my fault because I didn't see the sign.
The engineer identified a technical fault in the wiring that caused the entire system to shut down unexpectedly.
While the structural fault in the bridge was minor, the public's loss of confidence in the construction firm proved to be a much more difficult problem to repair.
From Middle English faute, faulte, from Anglo-Norman faute, Old French faute, from Vulgar Latin fallita (“shortcoming”), feminine of fallitus, in place of Latin falsus, perfect passive participle of fallō (“deceive”). Displaced native Middle English schuld, schuild (“fault”) (from Old English scyld (“fault”)), Middle English lac (“fault, lack”) (from Middle Dutch lak (“lack, fault”)), Middle English last (“fault, vice”) (from Old Norse lǫstr (“fault, vice, crime”)). Compare French faute (“fault, foul”), Portuguese falta (“lack, shortage”) and Spanish falta (“lack, absence”). More at fail, false.
Uncountable when referring to responsibility ('it's my fault'); countable when referring to specific defects or geological fractures.
I have the fault for the mistakeIt is my faultLearners often translate directly from other languages using 'have' instead of the standard 'it is [possessive] fault' construction.