Source : Webster's Revised Unabridged Dictionary (1913)

Reef \Reef\ (r?f), n. [Akin to D. rif, G. riff, Icel. rif, Dan.
   rev; cf. Icel. rifa rift, rent, fissure, rifa to rive, bear.
   Cf. {Rift}, {Rive}.]
   1. A chain or range of rocks lying at or near the surface of
      the water. See {Coral reefs}, under {Coral}.

   2. (Mining.) A large vein of auriferous quartz; -- so called
      in Australia. Hence, any body of rock yielding valuable
      ore.

   {Reef builder} (Zo["o]l.), any stony coral which contributes
      material to the formation of coral reefs.

   {Reef heron} (Zo["o]l.), any heron of the genus {Demigretta};
      as, the blue reef heron ({D. jugularis}) of Australia.