The Collaborative International Dictionary of English v.0.48:

Nutria \Nu"tri*a\, n. [Sp. nutria an otter, fr. L. lutra,
   lytra.]
   The fur of the coypu. See Coypu.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Coypu \Coy"pu\ (koi"p??), n. [Native name.] (Zool.)
   A South American rodent (Myopotamus coypus), allied to the
   beaver. It produces a valuable fur called nutria. [Written
   also coypou.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

nutria
    n 1: aquatic South American rodent resembling a small beaver;
         bred for its fur [syn: coypu, nutria, Myocastor
         coypus]