tattletale
nounUK /ˈtætəlteɪl/
US /ˈtætəlteɪl/
A tattletale is a kid who tells on others to get them in trouble.
My little brother is such a tattletale that he told Mom I ate a cookie before dinner.
RELATED WORDS
OTHER MEANINGS
2. A person who reveals private or secret information about others.
The office tattletale told the boss about everyone's long lunch breaks.
3. As an adjective, describing someone who tells on others.
Her tattletale behavior made the other kids avoid her at recess.
4. A child's term for someone who reports minor misbehavior to an adult.
Don't be a tattletale; just talk to me about it first.