The Collaborative International Dictionary of English v.0.48:

Cymbal \Cym"bal\ (s?m"bal). n. [OE. cimbale, simbale, OF.
   cimbale, F. cymbale, L. cymbalum, fr. Gr. ky`mbalon, fr.
   ky`mbh, ky`mbos, anything hollow, hollow vessel, basin, akin
   to Skr. kubha pot. Cf. Chime.]
   1. A musical instrument used by the ancients. It is supposed
      to have been similar to the modern kettle drum, though
      perhaps smaller.
      [1913 Webster]

   2. A musical instrument of brass, shaped like a circular dish
      or a flat plate, with a handle at the back; -- used in
      pairs to produce a sharp ringing sound by clashing them
      together.
      [1913 Webster]

   Note: In orchestras, one cymbal is commonly attached to the
         bass drum, and the other heid in the drummer's left
         hand, while his right hand uses the drumstick.
         [1913 Webster]

   3. A musical instrument used by gypsies and others, made of
      steel wire, in a triangular form, on which are movable
      rings.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cymbal
    n 1: a percussion instrument consisting of a concave brass disk;
         makes a loud crashing sound when hit with a drumstick or
         when two are struck together

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "cymbal":
   apple fritter, battery, beignet, beignet aux pommes, bells,
   bismarck, bones, castanets, celesta, chime, chimes, clappers,
   crash cymbal, cruller, cymbals, doughnut, fastnacht,
   finger cymbals, friedcake, fritter, gamelan, glockenspiel, gong,
   handbells, idiophone, lyra, maraca, marimba, metallophone, olykoek,
   orchestral bells, percussion, percussion instrument, percussions,
   percussive, raised doughnut, rattle, rattlebones, sinker, sizzler,
   snappers, tam-tam, tintinnabula, tonitruone, triangle,
   tubular bells, twister, vibes, vibraphone, xylophone