n. [ AS. ræt; akin to D. rat, OHG. rato, ratta, G. ratte, ratze, OLG. ratta, LG. & Dan. rotte, Sw. råtta, F. rat, Ir. & Gael radan, Armor. raz, of unknown origin. Cf. Raccoon. ] 1. (Zool.) 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 ]

☞ “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 (Zool.), any Indian rodent of the genus Rhizomys. --
Beaver rat,
Coast rat. (Zool.) See under Beaver and Coast. --
Blind rat (Zool.), the mole rat. --
Cotton rat (Zool.), 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 (Zool.), the potoroo. --
Norway rat (Zool.), the common brown rat. See Rat. --
Pouched rat. (Zool.) (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. (Zool.) 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 (Zool.), a large colubrine snake (Ptyas mucosus) very common in India and Ceylon. It enters dwellings, and destroys rats, chickens, etc. --
Spiny rat (Zool.), any South American rodent of the genus Echinomys. --
To smell a rat. See under Smell. --
Wood rat (Zool.), any American rat of the genus Neotoma, especially Neotoma Floridana, common in the Southern United States. Its feet and belly are white. [ 1913 Webster ]

v. i. [ imp. & p. p. Ratted; p. pr. & vb. n. Ratting. ] 1. In English politics, to desert one's party from interested motives; to forsake one's associates for one's own advantage; in the trades, to work for less wages, or on other conditions, than those established by a trades union. [ 1913 Webster ]

Coleridge . . . incurred the reproach of having ratted, solely by his inability to follow the friends of his early days. De Quincey. [ 1913 Webster ]

2. To catch or kill rats. [ 1913 Webster ]

2. To be an informer (against an associate); to inform (on an associate); to squeal; -- used commonly in the phrase to rat on. [ PJC ]

n. [ Maori. ] (Bot.) A New Zealand forest tree (Metrosideros robusta), also, its hard dark red wood, used by the Maoris for paddles and war clubs. [ 1913 Webster ]

n. The quality or state of being ratable. [ 1913 Webster ]

a. 1. Capable of being rated, or set at a certain value. [ 1913 Webster ]

Twenty orae were ratable to [ at ] two marks of silver. Camden. [ 1913 Webster ]

2. Liable to, or subjected by law to, taxation; as, ratable estate. [ 1913 Webster ]

3. Made at a proportionate rate; as, ratable payments. -- Rat"a*ble*ness, n. -- Rat"a*bly, adv. [ 1913 Webster ]

n. a structure which may be rated, or set at a certain value, for the purpose of taxation, usually based on the value; as, with the deterioration of the center cities, the loss of ratables worsened the situation by removing valuable sources of tax revenue. [ PJC ]

n. [ F., fr. Malay arak arrack + tāfīa a spirit distilled from molasses. ] A spirituous liquor flavored with the kernels of cherries, apricots, peaches, or other fruit, spiced, and sweetened with sugar; -- a term applied to the liqueurs called noyau, curaçao, etc. [ Written also ratifia and ratafee. ] [ 1913 Webster ]

n. See Rattan. [ 1913 Webster ]

n. (Bot.) Same as Rhatany. [ 1913 Webster ]

‖n. [ F. ] The iterative sound of beating a drum, or of a galloping horse. [ 1913 Webster ]