rat

any of various long-tailed rodents similar to but larger than a mouse

a pad (usually made of hair) worn as part of a woman's coiffure

one who reveals confidential information in return for money

a person who is deemed to be despicable or contemptible

someone who works (or provides workers) during a strike

give away information about somebody

catch rats, especially with dogs

give (hair) the appearance of being fuller by using a rat

take the place of work of someone on strike

employ scabs or strike breakers in

desert one's party or group of friends, for example, for one's personal advantage