The Collaborative International Dictionary of English v.0.48:

Mohair \Mo"hair`\, n. [F. moire, perh. from Ar. mukhayyar a kind
   of coarse camelot or haircloth; but prob. fr. L. marmoreus of
   marble, resembling marble. Cf. Moire, Marble.]
   The long silky hair or wool of the Angora goat of Asia Minor;
   also, a fabric made from this material, or an imitation of
   such fabric.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mohair
    n 1: fabric made with yarn made from the silky hair of the
         Angora goat