The Collaborative International Dictionary of English v.0.48:

Mouse \Mouse\ (mous), n.; pl. Mice (m[imac]s). [OE. mous, mus,
   AS. m[=u]s, pl. m[=y]s; akin to D. muis, G. maus, OHG. &
   Icel. m[=u]s, Dan. muus, Sw. mus, Russ. muishe, L. mus, Gr.
   my^s, Skr. m[=u]sh mouse, mush to steal. [root]277. Cf.
   Muscle, Musk.]
   1. (Zool.) Any one of numerous species of small rodents
      belonging to the genus Mus and various related genera of
      the family Muridae. The common house mouse (Mus
      musculus) is found in nearly all countries. The American
      white-footed mouse, or deer mouse (Peromyscus
      leucopus, formerly Hesperomys leucopus) sometimes lives
      in houses. See Dormouse, Meadow mouse, under Meadow,
      and Harvest mouse, under Harvest.
      [1913 Webster]

   2. (Naut.)
      (a) A knob made on a rope with spun yarn or parceling to
          prevent a running eye from slipping.
      (b) Same as 2d Mousing, 2.
          [1913 Webster]

   3. A familiar term of endearment. --Shak.
      [1913 Webster]

   4. A dark-colored swelling caused by a blow. [Slang]
      [1913 Webster]

   5. A match used in firing guns or blasting.
      [1913 Webster]

   Field mouse, Flying mouse, etc. See under Field,
      Flying, etc.

   Mouse bird (Zool.), a coly.

   Mouse deer (Zool.), a chevrotain, as the kanchil.

   Mouse galago (Zool.), a very small West American galago
      (Galago murinus). In color and size it resembles a
      mouse. It has a bushy tail like that of a squirrel.

   Mouse hawk. (Zool.)
      (a) A hawk that devours mice.
      (b) The hawk owl; -- called also mouse owl.

   Mouse lemur (Zool.), any one of several species of very
      small lemurs of the genus Chirogaleus, found in
      Madagascar.

   Mouse piece (Cookery), the piece of beef cut from the part
      next below the round or from the lower part of the latter;
      -- called also mouse buttock.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mouse deer
    n 1: very small hornless deer-like ruminant of tropical Asia and
         west Africa [syn: chevrotain, mouse deer]