Fault is a noun meaning:
1. A defect or imperfection
2. Responsibility for wrongdoing or failure
3. (Geology) A fracture in the continuity of a rock formation
4. (Tennis) An invalid serve
As a verb, fault means to criticize or blame someone.
Common phrases:
- At fault: responsible for a mistake
- Find fault with: to criticize
- Fault line: a line of weakness