Tattletale (noun)

A person who tells secrets or reveals information about others' private or wrong doings.

Origin:

This word is derived from the combination of the words "tattle" and "tale" . it was first used in the 17th century.

Examples:

1. He was always a tattletale and would tell on his classmates for the slightest infraction.
2. She was known as the class tattletale, always quick to point out when someone broke a rule.
3. The tattletale got in trouble for spreading rumors about her classmates.
4. The tattletale was always eager to report any misbehavior to the teacher.
5. He was always tattletale and it made him many enemies.