The Collaborative International Dictionary of English v.0.48:

Gorgon \Gor"gon\ (g[^o]r"g[o^]n), n. [L. Gorgo, -onis, Gr.
   Gorgw`, fr. gorgo`s terrible.]
   1. (Gr. Myth.) One of three fabled sisters, Stheno, Euryale,
      and Medusa, with snaky hair and of terrific aspect, the
      sight of whom turned the beholder to stone. The name is
      particularly given to Medusa.
      [1913 Webster]

   2. Anything very ugly or horrid. --Milton.
      [1913 Webster]

   3. (Zool.) The brindled gnu. See Gnu.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gorgon \Gor"gon\, a.
   Like a Gorgon; very ugly or terrific; as, a Gorgon face.
   --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Gorgon
    n 1: (Greek mythology) any of three winged sister monsters and
         the mortal Medusa who had live snakes for hair; a glance at
         Medusa turned the beholder to stone

The Devil's Dictionary (1881-1906):

GORGON, n.

    The Gorgon was a maiden bold
    Who turned to stone the Greeks of old
    That looked upon her awful brow.
    We dig them out of ruins now,
    And swear that workmanship so bad
    Proves all the ancient sculptors mad.