- 1a small animal with a long tail, that looks like a large mouse, usually considered a pest (= an animal that is disliked because it destroys food or spreads disease) rat poison The police are all over town. He's caught, like a rat in a trap. compare rug rat
- 2(informal) (disapproving) an unpleasant person, especially one who is not loyal or who tricks someone You mean he just walked out on her after fifteen years? What a rat! Idioms
used to talk about people who leave an organization, a company, etc. that is having difficulties, without caring about the people who are left
to suspect that something is wrong about a situation
Check pronunciation: rat