The Collaborative International Dictionary of English v.0.48:

Hare \Hare\, n. [AS. hara; akin to D. haas, G. hase, OHG. haso,
   Dan. & Sw. hare, Icel. h[=e]ri, Skr. [,c]a[,c]a. [root]226.]
   [1913 Webster]
   1. (Zool.) A rodent of the genus Lepus, having long hind
      legs, a short tail, and a divided upper lip. It is a timid
      animal, moves swiftly by leaps, and is remarkable for its
      fecundity.
      [1913 Webster]

   Note: The species of hares are numerous. The common European
         hare is Lepus timidus. The northern or varying hare
         of America (Lepus Americanus), and the prairie hare
         (Lepus campestris), turn white in winter. In America,
         the various species of hares are commonly called
         rabbits.
         [1913 Webster]

   2. (Astron.) A small constellation situated south of and
      under the foot of Orion; Lepus.
      [1913 Webster]

   Hare and hounds, a game played by men and boys, two, called
      hares, having a few minutes' start, and scattering bits of
      paper to indicate their course, being chased by the
      others, called the hounds, through a wide circuit.

   Hare kangaroo (Zool.), a small Australian kangaroo
      (Lagorchestes Leporoides), resembling the hare in size
      and color,

   Hare's lettuce (Bot.), a plant of the genus Sonchus, or
      sow thistle; -- so called because hares are said to eat it
      when fainting with heat. --Dr. Prior.

   Jumping hare. (Zool.) See under Jumping.

   Little chief hare, or Crying hare. (Zool.) See Chief
      hare.

   Sea hare. (Zool.) See Aplysia.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sea hare \Sea" hare`\ (Zool.)
   Any tectibranchiate mollusk of the genus Aplysia. See
   Aplysia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sea hare
    n 1: naked marine gastropod having a soft body with reduced
         internal shell and two pairs of ear-like tentacles [syn:
         sea hare, Aplysia punctata]