sea bird, seabird, seafowl - a bird that frequents coastal waters and the open ocean: gulls; pelicans; gannets; cormorants; albatrosses; petrels; etc.

Gaviiformes, order Gaviiformes - large aquatic birds: loons and some extinct forms

loon, diver - large somewhat primitive fish-eating diving bird of the northern hemisphere having webbed feet placed far back; related to the grebes