A wrongdoer is someone who does something harmful, dishonest, or against the rules. The word covers everyone from a student who copies homework to a thief who steals from a store. A wrongdoer might break a law, violate a rule, or act in a way that hurts others.

The word appears often in stories, news reports, and discussions about fairness. When a principal investigates vandalism at school, she's trying to identify the wrongdoer. When a judge sentences someone for a crime, that person is the wrongdoer in that case. Historical documents and older books use the term frequently: “The wrongdoers were brought to justice.”

Notice that wrongdoer focuses on the action, not the person's entire character. Someone might be a wrongdoer in one situation but still be capable of better choices. The word also applies regardless of whether the person gets caught. You're a wrongdoer the moment you commit the wrong act, not just if someone discovers it. A wrongdoing is the harmful or dishonest act itself.