Close relative of a mouse
• One of 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. decumanus), the black rat (M. rattus), and the roof rat (M. Alexandrinus). These were introduced into America from the Old World. • A round and tapering mass of hair, or similar material, used by women to support the puffs and rolls of their natural hair.