a large extinct flightless auk (seabird) of the North Atlantic, resembling a giant razorbill. The great auk was the original ‘penguin’; many were taken for food, and the last individuals were killed on an islet off Iceland in 1844.
Alca (or Pinguinus) impennis, family Alcidae
great auk in other Oxford dictionaries
Definition of great auk in the US English dictionary