Squealer (noun)

A person who tells secrets or informs on others, especially to the authorities.

Origin:

Derived from the verb "squeal" which means "to make a high-pitched cry or noise".

Examples:

1. The police were able to catch the thief because of the squealer.
2. He was known as a squealer and no one trusted him.
3. The squealer was the one who reported the illegal activities of the company to the authorities.
4. The squealer was afraid of getting caught and gave the information to the police.
5. The squealer couldn't stand the guilt of not telling what he knew, so he reported it.