tattler
/ˈtætlər/
noun
- A person who tells secrets or reports others' misdeeds, often in a petty or annoying way.
- In the office, the tattler was avoided by coworkers who didn't trust him.
- The kids called him a tattler because he always told the teacher when someone broke a rule.
- She was known as a tattler in the neighborhood, always spreading stories about her neighbors.