The Collaborative International Dictionary of English v.0.48:

Ibex \I"bex\ ([imac]"b[e^]ks), n.; pl. E. Ibexes
   ([imac]"b[e^]ks*[e^]z), L. Ibices ([imac]b"[i^]*s[=e]z).
   [L., a kind of goat, the chamois.] (Zool.)
   One of several species of wild goats having very large,
   recurved horns, transversely ridged in front; -- called also
   steinbok.
   [1913 Webster]

   Note: The Alpine ibex (Capra ibex) is the best known. The
         Spanish, or Pyrenean, ibex (Capra Hispanica) has
         smoother and more spreading horns.
         [1913 Webster]