accuse
To say someone did something wrong or broke a rule.
To accuse someone means to say that you believe they did something wrong or broke a rule. When you accuse your brother of eating the last cookie, you're claiming he's the one who took it. When a teacher accuses a student of not doing their homework, she's saying she thinks the student didn't complete the assignment.
Accusing someone is serious because you're essentially blaming them for something. It's different from wondering or suspecting: an accusation is a direct statement. In a courtroom, a prosecutor accuses someone of committing a crime. On the playground, one friend might accuse another of cheating at four square.
The word carries weight because accusations affect how others see someone. A false accusation can damage someone's reputation unfairly. If you stand accused of something, people are claiming you did it, and you may need to defend yourself or explain what really happened.
Sometimes people say “don't accuse me!” when they feel someone is blaming them without good reason. A person who makes an accusation should have evidence or a good reason for their claim, not just a guess or a feeling.