The Collaborative International Dictionary of English v.0.48:

Ballet \Bal"let`\ (b[a^]l"l[asl]` or b[a^]l"l[e^]t; 277), n.
   [F., a dim. of bal dance. See 2d Ball, n.]
   1. An artistic dance performed as a theatrical entertainment,
      or an interlude, by a number of persons, usually women.
      Sometimes, a scene accompanied by pantomime and dancing.
      [1913 Webster]

   2. The company of persons who perform the ballet.
      [1913 Webster]

   3. (Mus.) A light part song, or madrigal, with a fa la burden
      or chorus, -- most common with the Elizabethan madrigal
      composers; -- also spelled ballett.
      [1913 Webster]

   4. (Her.) A bearing in coats of arms, representing one or
      more balls, which are denominated bezants, plates, etc.,
      according to color.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ballet
    n 1: a theatrical representation of a story that is performed to
         music by trained dancers [syn: ballet, concert dance]
    2: music written for a ballet

Moby Thesaurus II by Grady Ward, 1.0:

125 Moby Thesaurus words for "ballet":
   Broadway musical, Grand Guignol, Passion play, Singspiel, Tom show,
   antimasque, audience success, ballad opera, ballet divertissement,
   ballroom dancing, bomb, broadcast drama, burlesque show, charade,
   choreodrama, choreography, chorus show, classical ballet,
   cliff hanger, closet drama, comedy ballet, comedy drama,
   comic opera, critical success, dance, dance drama, dancing,
   daytime serial, dialogue, documentary drama, drama, dramalogue,
   dramatic play, dramatic series, duodrama, duologue, epic theater,
   experimental theater, extravaganza, failure, flop, gasser,
   giveaway, grand opera, happening, hit, hit show, hoofing,
   improvisational drama, legitimate drama, light opera, lyric drama,
   masque, melodrama, minstrel, minstrel show, miracle, miracle play,
   modern ballet, modern dance, monodrama, monologue, morality,
   morality play, music drama, musical, musical comedy, musical revue,
   musical stage, musical theater, mystery, mystery play, opera,
   opera ballet, opera bouffe, opera buffa, operetta, pageant,
   panel show, pantomime, pastoral, pastoral drama, piece, play,
   playlet, problem play, psychodrama, quiz show, radio drama, review,
   revue, sensational play, serial, show, sitcom, situation comedy,
   sketch, skit, soap, soap opera, sociodrama, song-and-dance act,
   song-play, spectacle, stage play, stage show, straight drama,
   success, suspense drama, tableau, tableau vivant, talk show,
   tap dancing, teleplay, television drama, television play,
   terpsichore, theater of cruelty, total theater, variety show,
   vaudeville, vaudeville show, vehicle, word-of-mouth success,
   work