Usage: usually capitalized C
: a large scarlet-billed tern (Sterna caspia or Hydropygne caspia) widely distributed in the northern hemisphere with one subspecies occurring in much of northern No. America
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Caspian tern,
a large tern with a shining black crest and pearl-gray back and wings. The Caspian tern is found along seacoasts throughout the world.
Useful english dictionary. 2012.