The Collaborative International Dictionary of English v.0.48:

Rabbit \Rab"bit\ (r[a^]b"b[i^]t), n. [OE. rabet, akin to OD.
   robbe, robbeken.] (Zool.)
   Any of the smaller species of the genus Lepus, especially the
   common European species (Lepus cuniculus), which is often
   kept as a pet, and has been introduced into many countries.
   It is remarkably prolific, and has become a pest in some
   parts of Australia and New Zealand.
   [1913 Webster]

   Note: The common American rabbit (Lepus sylvatica) is
         similar but smaller. See Cottontail, and Jack
         rabbit, under 2d Jack. The larger species of Lepus
         are commonly called hares. See Hare.
         [1913 Webster]

   Angora rabbit (Zool.), a variety of the domestic rabbit
      having long, soft fur.

   Rabbit burrow, a hole in the earth made by rabbits for
      shelter and habitation.

   Rabbit fish. (Zool.)
   (a) The northern chimaera (Chimaera monstrosa).
   (b) Any one of several species of plectognath fishes, as the
       bur fish, and puffer. The term is also locally applied to
       other fishes.

   Rabbits' ears. (Bot.) See Cyclamen.

   Rabbit warren, a piece of ground appropriated to the
      breeding and preservation of rabbits. --Wright.

   Rock rabbit.
   (a) (Zool.) See Daman, and Klipdas.
   (b) the pika.

   Welsh rabbit, a dish of which the chief constituents are
      melted cheese over toasted bread, flavored in various
      ways, as with ale, beer, milk, or spices. The name is
      popularly said to be a corruption of Welsh rare bit, but
      it is probably merely a humorous designation; -- also
      called Welsh rarebit.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Welsh \Welsh\, a. [AS. w[ae]lisc, welisc, from wealh a stranger,
   foreigner, not of Saxon origin, a Welshman, a Celt, Gael;
   akin to OHG. walh, whence G. w[aum]lsch or welsch, Celtic,
   Welsh, Italian, French, Foreign, strange, OHG. walhisc; from
   the name of a Celtic tribe. See Walnut.]
   Of or pertaining to Wales, or its inhabitants. [Sometimes
   written also Welch.]
   [1913 Webster]

   Welsh flannel, a fine kind of flannel made from the fleece
      of the flocks of the Welsh mountains, and largely
      manufactured by hand.

   Welsh glaive, or Welsh hook, a weapon of war used in
      former times by the Welsh, commonly regarded as a kind of
      poleax. --Fairholt. --Craig.

   Welsh mortgage (O. Eng. Law), a species of mortgage, being
      a conveyance of an estate, redeemable at any time on
      payment of the principal, with an understanding that the
      profits in the mean time shall be received by the
      mortgagee without account, in satisfaction of interest.
      --Burrill.

   Welsh mutton, a choice and delicate kind of mutton obtained
      from a breed of small sheep in Wales.

   Welsh onion (Bot.), a kind of onion (Allium fistulosum)
      having hollow inflated stalks and leaves, but scarcely any
      bulb, a native of Siberia. It is said to have been
      introduced from Germany, and is supposed to have derived
      its name from the German term w[aum]lsch foreign.

   Welsh parsley, hemp, or halters made from hemp. [Obs. &
      Jocular] --J. Fletcher.

   Welsh rabbit. See under Rabbit.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Welsh rabbit
    n 1: cheese melted with ale or beer served over toast [syn:
         Welsh rarebit, Welsh rabbit, rarebit]