Source : Webster's Revised Unabridged Dictionary (1913)

Oriel \O"ri*el\, n. [OF. oriol gallery, corridor, LL. oriolum
   portico, hall, prob. fr. L. aureolus gilded, applied to an
   apartment decorated with gilding. See {Oriole}.] [Formerly
   written also {oriol}, {oryal}, {oryall}.]
   1. A gallery for minstrels. [Obs.] --W. Hamper.

   2. A small apartment next a hall, where certain persons were
      accustomed to dine; a sort of recess. [Obs.] --Cowell.

   3. (Arch.) A bay window. See {Bay window}.

            The beams that thro' the oriel shine Make prisms in
            every carven glass.                   --Tennyson.

   Note: There is no generally admitted difference between a bay
         window and an oriel. In the United States the latter
         name is often applied to bay windows which are small,
         and either polygonal or round; also, to such as are
         corbeled out from the wall instead of resting on the
         ground.

Source : WordNet®

oriel
     n : a projecting bay window corbeled or cantilevered out from a
         wall [syn: {oriel window}]