The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

   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 or the more modern scherzo;
         then the quick finale in the rondo form. But both form
         and order are sometimes exceptional.
         [1913 Webster]

WordNet (r) 3.0 (2006):

sonata
    n 1: a musical composition of 3 or 4 movements of contrasting
         forms

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "sonata":
   Nachtmusik, absolute music, adaptation, air varie, aleatory,
   aleatory music, arrangement, chamber music, chamber orchestra,
   composition, descant, electronic music, etude, exercise,
   harmonization, incidental music, instrumental music, invention,
   nocturne, opus, orchestration, piece, production, program music,
   ricercar, score, sonatina, string orchestra, string quartet, study,
   theme and variations, trio, variation, work



The Free On-line Dictionary of Computing (30 December 2018):

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)