ETYM AS. raet; akin to Dutch rat, Old High Germ. rato, ratta, German ratte, ratze, OLG. ratta, LG. and Dan. rotte, Swed. ratta, French rat, Irish and Gael. radan, Armor. raz, of unknown origin. Related to Raccoon.
Any of numerous long-tailed rodents (especially of the families Muridae and Cricetidae) larger than mice and usually with scaly, naked tails. The genus Rattus in the family Muridae includes the rats found in human housing.
The brown rat R. norvegicus is about 20 cm/8 in long with a tail of almost equal length. It is believed to have originated in central Asia, and is now found worldwide after being transported from Europe by ships. The black rat R. rattus, responsible for the plague, is smaller than the brown rat, but has larger ears and a longer, more pointed snout. It does not interbreed with brown rats. The pack rat or wood rat, genus Neotoma, is common throughout North America and there are seven different species. Their dens, made of partly eaten plants, dung, and miscellaneous objects, are known as middens and can be up to 2 m/6.5 ft across and 20–30 cm/8–12 in high. The rats’ crystallized urine preserves the midden, in some cases for up to 40,000 years.
Any of various long-tailed rodents similar to but larger than a mouse.
1. To catch rats, esp. with dogs.
2. To desert one's party or group of friends, for example, for one's personal advantage.
3. To employ scabs or strike breakers in (an industry).
4. To give (hair) the appearance of being fuller by using a rat.