The Collaborative International Dictionary of English v.0.48:

oystercatcher \oystercatcher\, oyster catcher \oyster catcher\n.
   (Zool.),
   Any one of several species of wading birds of the genus
   Haematopus having stout legs and bill and mostly
   black-and-white plumage, which frequent seashores and feed
   upon oysters and other shellfish. The European species
   (Haematopus ostralegus), the common American species
   (Haematopus palliatus), and the California, or black,
   oyster catcher (Haematopus Bachmani) are the best known.

   Syn: oyster plover.
        [1913 Webster]

WordNet (r) 3.0 (2006):

oystercatcher
    n 1: black-and-white shorebird with stout legs and bill; feed on
         oysters etc. [syn: oystercatcher, oyster catcher]