The Collaborative International Dictionary of English v.0.48:

hawkbill \hawk"bill`\, hawksbill \hawks"bill`\(-b[i^]l`), n.
   (Zool.)
   A sea turtle (Eretmochelys imbricata), which yields the
   best quality of tortoise shell; -- called also caret.

   Syn: hawksbill turtle, hawkbill, tortoiseshell turtle,
        Eretmochelys imbricata.
        [1913 Webster]

WordNet (r) 3.0 (2006):

hawkbill
    n 1: pugnacious tropical sea turtle with a hawk-like beak;
         source of food and the best tortoiseshell [syn: hawksbill
         turtle, hawksbill, hawkbill, tortoiseshell turtle,
         Eretmochelys imbricata]