Rattus norvegicus

Rat Rat (r[a^]t), n. [AS. r[ae]t; akin to D. rat, OHG. rato, ratta, G. ratte, ratze, OLG. ratta, LG. & Dan. rotte, Sw. r[*a]tta, F. rat, Ir. & Gael radan, Armor. raz, of unknown origin. Cf. {Raccoon}.] 1. (Zo["o]l.) One of several species of small rodents of the genus {Rattus} (formerly included in {Mus}) and allied genera, of the family {Muridae}, distinguished from mice primarily by being larger. They infest houses, stores, and ships, especially the Norway rat, also called {brown rat}, ({Rattus norvegicus} formerly {Mus decumanus}), the black rat ({Rattus rattus} formerly {Mus rattus}), and the roof rat (formerly {Mus Alexandrinus}, now included in {Rattus rattus}). These were introduced into America from the Old World. The white rat used most commonly in laboratories is primarily a strain derived from {Rattus rattus}. [1913 Webster +PJC]

2. A round and tapering mass of hair, or similar material, used by women to support the puffs and rolls of their natural hair. [Local, U.S.] [1913 Webster]

3. One who deserts his party or associates; hence, in the trades, one who works for lower wages than those prescribed by a trades union. [Cant] [1913 Webster]

Note: ``It so chanced that, not long after the accession of the house of Hanover, some of the brown, that is the German or Norway, rats, were first brought over to this country (in some timber as is said); and being much stronger than the black, or, till then, the common, rats, they in many places quite extirpated the latter. The word (both the noun and the verb to rat) was first, as we have seen, leveled at the converts to the government of George the First, but has by degrees obtained a wider meaning, and come to be applied to any sudden and mercenary change in politics.'' --Lord Mahon. [1913 Webster]

{Bamboo rat} (Zo["o]l.), any Indian rodent of the genus {Rhizomys}.

{Beaver rat}, {Coast rat}. (Zo["o]l.) See under {Beaver} and {Coast}.

{Blind rat} (Zo["o]l.), the mole rat.

{Cotton rat} (Zo["o]l.), a long-haired rat ({Sigmodon hispidus}), native of the Southern United States and Mexico. It makes its nest of cotton and is often injurious to the crop.

{Ground rat}. See {Ground Pig}, under {Ground}.

{Hedgehog rat}. See under {Hedgehog}.

{Kangaroo rat} (Zo["o]l.), the potoroo.

{Norway rat} (Zo["o]l.), the common brown rat. See {Rat}.

{Pouched rat}. (Zo["o]l.) (a) See {Pocket Gopher}, under {Pocket}. (b) Any African rodent of the genus {Cricetomys}.

{Rat Indians} (Ethnol.), a tribe of Indians dwelling near Fort Ukon, Alaska. They belong to the Athabascan stock.

{Rat mole}. (Zo["o]l.) See {Mole rat}, under {Mole}.

{Rat pit}, an inclosed space into which rats are put to be killed by a dog for sport.

{Rat snake} (Zo["o]l.), a large colubrine snake ({Ptyas mucosus}) very common in India and Ceylon. It enters dwellings, and destroys rats, chickens, etc.

{Spiny rat} (Zo["o]l.), any South American rodent of the genus {Echinomys}.

{To smell a rat}. See under {Smell}.

{Wood rat} (Zo["o]l.), any American rat of the genus {Neotoma}, especially {Neotoma Floridana}, common in the Southern United States. Its feet and belly are white. [1913 Webster]