\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.
2. [pl. {Medusae}.] (Zo["o]l.) Any free swimming acaleph; a
   jellyfish.
Note: The larger medus[ae] belong to the Discophora, and are
      sometimes called {covered-eyed medus[ae]}; others,
      known as {naked-eyed medus[ae]}, belong to the
      Hydroidea, and are usually developed by budding from
      hidroids. See {Discophora}, {Hydroidea}, and
      {Hydromedusa}.
{Medusa bud} (Zo["o]l.), one of the buds of a hydroid,
   destined to develop into a gonophore or medusa. See
   {Athecata}, and {Gonotheca}.
{Medusa's head}.
   (a) (Zo["o]l.) An astrophyton.
   (b) (Astron.) A cluster of stars in the constellation
       Perseus. It contains the bright star Algol.