Varieties of rats include: white, black, brown, house, laboratory, longtailed, water, swamp, desert, marsh, tree, giant, field, bamboo, cotton, kangaroo, jerboa, river, pack, big-eared, short-eared, red-nosed.
*A deserter or betrayer
One who betrays:betrayer, double-crosser, Judas, traitor. See trust
One who gives incriminating information about others:informant, informer, tattler, tattletale. (Informal) tipster. (Slang) fink, snitch, snitcher, squealer, stoolie, stool pigeon. See knowledge, law
A person who has defected:apostate, defector, deserter, recreant, renegade, runagate, tergiversator, turncoat. See approach
To abandon one's cause or party usually to join another:apostatize, defect, desert3, renegade, tergiversate, turn. Idioms: change sides, turn one's coat. See approach, trust
To be treacherous to.Also used with on: betray, double-cross. (Slang) sell out. Idiom: sell down the river . See trust
To give incriminating information about others, especially to the authorities:inform, talk, tattle, tip3 (off). (Informal) fink. (Slang) sing, snitch, squeal, stool. Idiom: blow the whistle. See knowledge, law