Dictionary definition · rat
noun
- any of various long-tailed rodents similar to but larger than a mouse
- someone who works (or provides workers) during a strike
- a person who is deemed to be despicable or contemptible"only a rotter would do that"
- one who reveals confidential information to the police or other authority
- a pad (usually made of hair) worn as part of a woman's coiffure
verb
- desert one's party or group of friends, for example, for one's personal advantage
- employ scabs or strike breakers in
- take the place of work of someone on strike
- give (hair) the appearance of being fuller by using a rat
- catch rats, especially with dogs
- give away information about somebody"He told on his classmate who had cheated on the exam"
Source: Open English WordNet (CC BY 4.0).