Source : Webster's Revised Unabridged Dictionary (1913)

Sonata \So*na"ta\, n. [It., fr. It. & L. sonare to sound. See
   {Sound} a noise.] (Mus.)
   An extended composition for one or two instruments,
   consisting usually of three or four movements; as,
   Beethoven's sonatas for the piano, for the violin and piano,
   etc.

   Note: The same general structure prevails in symphonies,
         instrumental trios, quartets, etc., and even in
         classical concertos. The sonata form, distinctively,
         characterizes the quick opening movement, which may
         have a short, slow introduction; the second, or slow,
         movement is either in the song or variation form; third
         comes the playful minuet of the more modern scherzo;
         then the quick finale in the rondo form. But both form
         and order are sometimes exceptional.

Source : WordNet®

sonata
     n : a musical composition of 3 or 4 movements of contrasting
         forms

Source : Free On-Line Dictionary of Computing

Sonata
     
         The code name for the major {Mac OS}
        release due in mid-1999.
     
       
     {(http://devworld.apple.com/mkt/informed/appledirections/mar97/roadmap.html)}.
     
        (1997-10-15)