Source : Webster's Revised Unabridged Dictionary (1913)

Sea swallow \Sea" swal"low\
   1. (Zo["o]l.)
      (a) The common tern.
      (b) The storm petrel.
      (c) The gannet.

   2. (Her.) See {Cornish chough}, under {Chough}.

Source : WordNet®

sea swallow
     n : common tern of Eurasia and America having white black and
         gray plumage [syn: {Sterna hirundo}]