The Collaborative International Dictionary of English v.0.48:

Mitt \Mitt\, n. [Abbrev. fr. mitten.]
   1. A mitten; also, a covering for the wrist and hand and not
      for the fingers, usually worn by women.
      [1913 Webster]

   2. (Baseball) A large glove, usually made of leather or
      similar material, with differing degrees of padding and
      usually some form of webbing in the large space between
      the thumb insert and the insert for the index finger; a
      baseball glove. It is used to assist in catching the
      baseball. The catcher's mitt has more padding and less
      webbing.
      [PJC]

   3. A hand; -- used mostly in slang expressions; as, keep your
      mitts off my box of chocolates!
      [PJC]

WordNet (r) 3.0 (2006):

mitt
    n 1: the (prehensile) extremity of the superior limb; "he had
         the hands of a surgeon"; "he extended his mitt" [syn:
         hand, manus, mitt, paw]
    2: the handwear used by fielders in playing baseball [syn:
       baseball glove, glove, baseball mitt, mitt]