Any species of longwinged marine birds of the genus
   Rhynchops, allied to the terns, but having the lower mandible
   compressed and much longer than the upper one. These birds fly rapidly
   along the surface of the water, with the lower mandible immersed, thus
   skimming out small fishes. The American species (R. nigra) is common on
   the southern coasts of the United States. Called also scissorbill, and
   shearbill.