The Collaborative International Dictionary of English v.0.48:

ivorybill \i"vo*ry*bill`\, Ivory-bill
\I"vo*ry-bill`\([imac]"v[-o]*r[y^]*b[i^]l`), n. (Zool.)
   A large, handsome, black-and-white North American woodpecker
   (Campephilus principalis), having a large, sharp,
   ivory-colored beak. Its general color is glossy black, with
   white secondaries, and a white dorsal stripe. The male has a
   large, scarlet crest. It is now rare, and found only in the
   Gulf States and Cuba.

   Syn: ivory-billed woodpecker, Campephilus principalis.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Woodpecker \Wood"peck`er\, n. (Zool.)
   Any one of numerous species of scansorial birds belonging to
   Picus and many allied genera of the family Picidae.
   [1913 Webster]

   Note: These birds have the tail feathers pointed and rigid at
         the tip to aid in climbing, and a strong chisellike
         bill with which they are able to drill holes in the
         bark and wood of trees in search of insect larvae upon
         which most of the species feed. A few species feed
         partly upon the sap of trees (see Sap sucker, under
         Sap), others spend a portion of their time on the
         ground in search of ants and other insects.
         [1913 Webster] The most common European species are the
         greater spotted woodpecker (Dendrocopus major), the
         lesser spotted woodpecker (Dendrocopus minor), and
         the green woodpecker, or yaffle (see Yaffle).
         [1913 Webster] The best-known American species are the
         pileated woodpecker (see under Pileated), the
         ivory-billed woodpecker (Campephilus principalis),
         which is one of the largest known species, the
         red-headed woodpecker, or red-head (Melanerpes
         erythrocephalus), the red-bellied woodpecker
         (Melanerpes Carolinus) (see Chab), the superciliary
         woodpecker (Melanerpes superciliaris), the hairy
         woodpecker (Dryobates villosus), the downy woodpecker
         (Dryobates pubescens), the three-toed, woodpecker
         (Picoides Americanus), the golden-winged woodpecker
         (see Flicker), and the sap suckers. See also
         Carpintero.
         [1913 Webster]

   Woodpecker hornbill (Zool.), a black and white Asiatic
      hornbill (Buceros pica) which resembles a woodpecker in
      color.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Campephilus principalis
    n 1: large black-and-white woodpecker of southern United States
         and Cuba having an ivory bill; nearly extinct [syn:
         ivorybill, ivory-billed woodpecker, Campephilus
         principalis]