The American Heritage® Dictionary of the English Language, 4th Edition
n. Either of two gray gulls (Rissa tridactyla or R. brevirostris) of northern Atlantic regions, that winter on the open ocean and nest in colonies on sea cliffs.
n. Either of two small gulls in the genus Rissa of the family Laridae that nest in colonies on sea cliffs and spend the winter on the open ocean.
the GNU version of the Collaborative International Dictionary of English
n. A northern gull (Rissa tridactyla), inhabiting the coasts of Europe and America. It is white, with black tips to the wings, and has only three toes.
The Century Dictionary and Cyclopedia
n. A gull of the genus Rissa, family Laridæ, having the hind toe unusually short or rudimentary, the wings extremely long, a bill with an acute decurved tip, and peculiarly colored primaries.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. small pearl-grey gull of northern regions; nests on cliffs and has a rudimentary hind toe
Word Usage
"Other uncommon species are golden eagle Aquila chrysaetos, redlegged kittiwake Rissa brevirostris (VU), and spotted greenshank Tringa guttifer (EN)."