rat

rat is a Noun

Definition:

[1] One of the several species of small rodents of the genus Mus and allied genera, larger than mice, that infest houses, stores, and ships, especially the Norway, or brown, rat (M. Alexandrinus). These were introduced into Anerica from the Old World.

[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.]

[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]