The Collaborative International Dictionary of English v.0.48:

Rehearsal \Re*hears"al\ (r?*h?rs"a), n.
   The act of rehearsing; recital; narration; repetition;
   specifically, a private recital, performance, or season of
   practice, in preparation for a public exhibition or exercise.
   --Chaucer.
   [1913 Webster]

         In rehearsal of our Lord's Prayer.       --Hooker.
   [1913 Webster]

         Here's marvelous convenient place for our rehearsal.
                                                  --Shak.
   [1913 Webster]

   Dress rehearsal (Theater), a private preparatory
      performance of a drama, opera, etc., in costume.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rehearsal
    n 1: a practice session in preparation for a public performance
         (as of a play or speech or concert); "he missed too many
         rehearsals"; "a rehearsal will be held the day before the
         wedding" [syn: rehearsal, dry run]
    2: (psychology) a form of practice; repetition of information
       (silently or aloud) in order to keep it in short-term memory

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "rehearsal":
   Gedankenexperiment, account, accounts, apprenticeship, audition,
   basic training, bench test, body count, breaking, breeding,
   capitulation, census, conditioning, copy, count, critique,
   cultivation, description, development, direction, discipline,
   dress rehearsal, drill, drilling, dry run, dwelling upon,
   elaboration, enumeration, exercise, fetching-up, flight test,
   fostering, going over, grooming, head count, hearing,
   housebreaking, improvement, in-service training, inventory,
   iteration, manual training, military training, mise-en-scene,
   mounting, narration, narrative, nose count, nurture, nurturing,
   on-the-job training, pilot plan, practical test, practice,
   practicing, preparation, production, raising, readying,
   reaffirmation, rearing, recap, recapitulation, recital, reckoning,
   recount, recountal, recounting, rehash, reissue, reiteration,
   relation, repeat, repertory, repetition, reprint, restatement,
   resume, retelling, review, road test, run-through, shakedown,
   shakedown cruise, sloyd, stage management, staging, statement,
   summary, summation, summing, summing up, tale-telling, telling,
   test flight, test run, training, trial run, tryout, upbringing,
   vocational education, vocational training, walk-through, workout,
   yarn spinning