muskrat

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A large aquatic rodent (Ondatra zibethica) of North America, related to the lemming and the vole and having a dense brown coat and musk glands under a broad flat tail. Also called musquash, water rat.
2. n. The fur of this rodent.

Century Dictionary and Cyclopedia

1. n. A large murine rodent quadruped, Fiber zibethicus, of the family Muridœ and subfamily Arvicolinœ: so called from its musky odor. It is of about the size of a small rabbit, of a very stout thick-set form and dark-brown color, grayish underneath, with small eyes and ears, large hind feet with webbed toes, and long naked scaly tail, compressed in the horizontal plane so as to present an upper and an under edge, and two broad sides. In the character of the fur, the scaly tail, and aquatic habits, the muskrat resembles the beaver, and is sometimes called muskbeaver; but its actual relationships are with the voles and lemmings. It is one of the commonest quadrupeds of North America, almost universally distributed throughout that continent, living in lakes, rivers, and pools, either in underground burrows in the banks, or in houses made of reeds, rushes, and grasses, as large as haycocks and of similar shape. The fur is of commercial value, and the animal is much hunted. Also called musquash and ondatra.
2. n. An insectivorous animal of musky odor likened to a rat, such as the European desman, Mygale pyrenaica, and the Indian musk-shrew or rat-tailed shrew, Sorex indicus or Crocidura myosura, also called Indian muskrat and monjourou.
3. n. A viverrine quadruped, the South African genet, Genetta felina.

Wiktionary

1. n. A large aquatic rodent, so called for its musky odour and because it resembles a rat; Ondatra zibethica.

GNU Webster's 1913

1. n. A North American aquatic fur-bearing rodent (Ondatra zibethica formerly Fiber zibethicus). It resembles a rat in color and having a long scaly tail, but the tail is compressed, the hind feet are webbed, and the ears are concealed in the fur. It has scent glands which secrete a substance having a strong odor of musk. Called also musquash, musk beaver, ondatra, and sometimes water rat.
2. n. The musk shrew.
3. n. The desman.

WordNet 3.0

1. n. the brown fur of a muskrat
2. n. beaver-like aquatic rodent of North America with dark glossy brown fur