Muskrat

n.
  1. (Zoöl.) 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. (Zoöl.) The musk shrew.
  3. (Zoöl.) The desman.