short-legged flightless birds of cold southern especially Antarctic regions having webbed feet and wings modified as flippers, Any species of the family Spheniscid‘ or Aptenodytid‘. (See Spheniscid‘ for technical characters.), Any of various stout, flightless aquatic birds of the family Spheniscidae, of the Southern Hemisphere, having flipperlike wings and webbed feet adapted for swimming and diving, short scalelike feathers, and white underparts with a dark back