Definition of Rat

Noun: rat rat

Any of various long-tailed rodents similar to but larger than a mouse
Someone who works (or provides workers) during a strike
- scab, strikebreaker, blackleg [Brit]
A person who is deemed to be despicable or contemptible
"kill the rat";
- rotter, dirty dog, skunk, stinker, stinkpot, bum [N. Amer], crumb, lowlife, scumbag, so-and-so, git [Brit], sleazeball, slimebag, scuzzbag [N. Amer], scuzzbucket [N. Amer], ratbag [Brit], sleazebag, scuzz [N. Amer], toad, scuzzball [N. Amer], dirtbag [US], slimeball
One who reveals confidential information to the police or other authority
"The mafia liquidated the rat";
- informer, betrayer, squealer, blabber
A pad (usually made of hair) worn as part of a woman's coiffure

Verb: rat (ratted,ratting) rat

Desert one's party or group of friends, for example, for one's personal advantage
(industry) employ scabs or strike breakers in
Take the place of work of someone on strike
- fink [N. Amer], scab, blackleg [Brit]
Give (hair) the appearance of being fuller by using a rat
Catch rats, especially with dogs
Give away information about somebody
- denounce, tell on, betray, give away, grass, shop, snitch, stag, squeak