A culprit is the person who did something wrong or caused a problem. When someone breaks a window and the principal asks “Who's the culprit?” she wants to know who threw the ball. When half the cookies disappear from the kitchen, your mom might investigate to find the culprit.

The word carries a sense of detective work and discovery. Scientists searching for the culprit behind an epidemic want to identify what's making people sick. A mechanic looking for the culprit in a car problem tries to figure out which part has failed. The word often appears when someone is trying to solve a mystery or assign responsibility.

While culprit can describe anyone responsible for something negative, from small mistakes to serious crimes, it's usually more lighthearted than words like “criminal” or “perpetrator.” You might call your little brother the culprit when you discover he ate your Halloween candy, but you probably wouldn't use culprit to describe someone who committed a violent crime. The word works best for situations where there's some wrongdoing to uncover, but not necessarily something truly awful.