n. & v.
n. 1 a any of several rodents of the genus Rattus (brown rat). b any similar rodent (muskrat; water-rat). 2 a deserter from a party, cause, difficult situation, etc.; a turncoat (from the superstition that rats desert a sinking ship). 3 colloq. an unpleasant person. 4 a worker who refuses to join a strike, or who blacklegs. 5 (in pl.) sl. an exclamation of contempt, annoyance, etc.
v.intr. (ratted, ratting) 1 (of a person or dog) hunt or kill rats. 2 colloq. desert a cause, party, etc. 3 (foll. by on) a betray; let down. b inform on. rat-catcher a person who rids buildings of rats etc. rat kangaroo Austral. any of various small ratlike marsupials of the family Potoroidae, having kangaroo-like hind limbs for jumping. rat race a fiercely competitive struggle for position, power, etc. rat's tail a thing shaped like a rat's tail, e.g. a tapering cylindrical file. rat-tail 1 the grenadier fish. 2 a horse with a hairless tail. 3 such a tail. rat-tail (or -tailed) spoon a spoon with a tail-like moulding from the handle to the back of the bowl.
[ OE rt & OF rat ]