The Collaborative International Dictionary of English v.0.48:

Gannet \Gan"net\, n. [OE. gant, AS. ganet, ganot, a sea fowl, a
   fen duck; akin to D. gent gander, OHG. ganazzo. See Gander,
   Goose.] (Zool.)
   One of several species of sea birds of the genus Sula,
   allied to the pelicans.
   [1913 Webster]

   Note: The common gannet of Europe and America (Sula
         bassana), is also called solan goose, chandel
         goose, and gentleman. In Florida the wood ibis is
         commonly called gannet.
         [1913 Webster]

   Booby gannet. See Sula.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gannet
    n 1: large heavily built seabird with a long stout bill noted
         for its plunging dives for fish