The Collaborative International Dictionary of English v.0.48:

Medusa \Me*du"sa\, n. [L., fr. Gr. ?.]
   1. (Class. Myth.) The Gorgon; or one of the Gorgons whose
      hair was changed into serpents, after which all who looked
      upon her were turned into stone.
      [1913 Webster]

   2. [pl. Medusae.] (Zool.) Any free swimming acaleph; a
      jellyfish.
      [1913 Webster]

   Note: The larger medusae belong to the Discophora, and are
         sometimes called covered-eyed medusae; others, known
         as naked-eyed medusae, belong to the Hydroidea, and
         are usually developed by budding from hydroids. See
         Discophora, Hydroidea, and Hydromedusa.
         [1913 Webster]

   Medusa bud (Zool.), one of the buds of a hydroid, destined
      to develop into a gonophore or medusa. See Athecata, and
      Gonotheca.

   Medusa's head.
      (a) (Zool.) An astrophyton.
      (b) (Astron.) A cluster of stars in the constellation
          Perseus. It contains the bright star Algol.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Medusa
    n 1: (Greek mythology) a woman transformed into a Gorgon by
         Athena; she was slain by Perseus
    2: one of two forms that coelenterates take: it is the free-
       swimming sexual phase in the life cycle of a coelenterate; in
       this phase it has a gelatinous umbrella-shaped body and
       tentacles [syn: medusa, medusoid, medusan]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "Medusa":
   Argus, Briareus, Cerberus, Charybdis, Circe, Cyclops, Echidna,
   Euryale, Gorgon, Harpy, Hydra, Loch Ness monster, Medea, Minotaur,
   Pegasus, Python, Scylla, Sphinx, Stheno, Talos, Typhon, bewitcher,
   centaur, charmer, chimera, cockatrice, dragon, drake, enchanter,
   enchantress, griffin, hippocampus, mermaid, merman, nixie, ogre,
   ogress, roc, salamander, satyr, sea horse, sea serpent, siren,
   spellbinder, troll, unicorn, vampire, werewolf, windigo,
   xiphopagus, zombie



U.S. Gazetteer Places (2000):

Medusa, NY -- U.S. Census Designated Place in New York
   Population (2000):    376
   Housing Units (2000): 183
   Land area (2000):     6.785919 sq. miles (17.575449 sq. km)
   Water area (2000):    0.073525 sq. miles (0.190430 sq. km)
   Total area (2000):    6.859444 sq. miles (17.765879 sq. km)
   FIPS code:            46426
   Located within:       New York (NY), FIPS 36
   Location:             42.434449 N, 74.127248 W
   ZIP Codes (1990):     12120
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Medusa, NY
    Medusa