nutria

noun

1. the only member (Myocastor coypus) of a family (Myocastoridae) of South American water-dwelling rodents with webbed feet and a long, almost hairless tail; coypu
2. its short-haired, soft, brown fur, often dyed to look like beaver

Etymology: Sp < L lutra, otter, altered (with l- after lutum, mire) < IE *udros, water animal: see otter