Rat

n. [A.-S. ræt, D. rat, O. H. Ger. rato, N. H. Ger. ratte, ratze, O. L. Ger. ratta, L. Ger. & Dan. rotte, Sw. råtta, Fr. & Pr. rat, Sp. & Pg. rato, It. ratto, Ir. & Gael. radan, Armor. raz.]

1Sense 1. (Zoöl.) One of several species of small, rodent mammals, of the genus Mus, larger than mice, that infest houses, stores, and ships. The brown rat is M. decumanus; the black rat, M. rattus. Of allied species is the musk-rat (Ondatra zibethicus), the American jumping-rat, of the genus Didomys, and the jerboa, or jumping rat, a species of Dipus.

2Sense 2. A round and tapering mass of hair, or similar material, used by ladies to give fullness to their natural hair.

3Sense 3. One who deserts his party or associates; hence, among printers, one who works at less than the established prices.

“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.

To smell a rat, to be suspicious; to be on the watch from suspicion, as a cat by the scent or noise of a rat.