Wordnet 3.0
NOUN (1)
1. 
 a bird that frequents coastal waters and the open ocean: gulls; 
 pelicans; 
 gannets; 
 cormorants; 
 albatrosses; 
 petrels; 
 etc.; 
[syn: seabird, sea bird, seafowl]
The Collaborative International Dictionary of English v.0.48:
Sea bird \Sea" bird`\ (Zool.)
   Any swimming bird frequenting the sea; a sea fowl.
   [1913 Webster]
WordNet (r) 3.0 (2006):
sea bird
    n 1: a bird that frequents coastal waters and the open ocean:
         gulls; pelicans; gannets; cormorants; albatrosses; petrels;
         etc. [syn: seabird, sea bird, seafowl]