The Collaborative International Dictionary of English v.0.48:

Performance \Per*form"ance\, n.
   The act of performing; the carrying into execution or action;
   execution; achievement; accomplishment; representation by
   action; as, the performance of an undertaking of a duty.
   [1913 Webster]

         Promises are not binding where the performance is
         impossible.                              --Paley.
   [1913 Webster]

   2. That which is performed or accomplished; a thing done or
      carried through; an achievement; a deed; an act; a feat;
      esp., an action of an elaborate or public character. "Her
      walking and other actual performances." --Shak. "His
      musical performances." --Macaulay.
      [1913 Webster]

   Syn: Completion; consummation; execution; accomplishment;
        achievement; production; work; act; action; deed;
        exploit; feat.
        [1913 Webster]

WordNet (r) 3.0 (2006):

performance
    n 1: a dramatic or musical entertainment; "they listened to ten
         different performances"; "the play ran for 100
         performances"; "the frequent performances of the symphony
         testify to its popularity" [syn: performance, public
         presentation]
    2: the act of presenting a play or a piece of music or other
       entertainment; "we congratulated him on his performance at
       the rehearsal"; "an inspired performance of Mozart's C minor
       concerto"
    3: the act of performing; of doing something successfully; using
       knowledge as distinguished from merely possessing it; "they
       criticised his performance as mayor"; "experience generally
       improves performance" [syn: performance, execution,
       carrying out, carrying into action]
    4: any recognized accomplishment; "they admired his performance
       under stress"; "when Roger Maris powered four home runs in
       one game his performance merits awe"
    5: process or manner of functioning or operating; "the power of
       its engine determines its operation"; "the plane's operation
       in high winds"; "they compared the cooking performance of
       each oven"; "the jet's performance conformed to high
       standards" [syn: operation, functioning, performance]

Moby Thesaurus II by Grady Ward, 1.0:

240 Moby Thesaurus words for "performance":
   Philharmonic concert, accomplished fact, accomplishment,
   accordance, achievement, acquittal, acquittance, act, acta, acting,
   action, adherence, administration, adventure, agency, aping,
   appearance, attainment, baccalaureate service, band concert,
   behavior, benefit, bill, blow, bringing to fruition, buffoonery,
   business, cantando, care, carrying out, celebration, ceremonial,
   ceremony, chamber concert, characterization, commencement,
   commission, completion, compliance, concert, conduct, conformance,
   conformity, consummation, convocation, coup, dealings, debut, deed,
   demeanor, demilegato, demonstration, deportment, direction,
   discharge, dispatch, display, doing, doings, driving, dumb show,
   effectiveness, effectuation, efficacy, effort, embodiment,
   empty formality, enacting, enactment, endeavor, engagement,
   enterprise, entertainment, execution, exercise, exercises, exhibit,
   exhibition, exploit, exposition, exposure, expression,
   fait accompli, farewell performance, feat, fingering, flesh show,
   formal, formality, fruition, fulfillment, function, functioning,
   gag, gest, gig, glissando, go, graduation, graduation exercises,
   ham, hammy acting, hand, handiwork, handling, heed, heeding, hoke,
   hokum, imitation, impersonation, implementation, inaugural,
   inauguration, incarnation, initiation, interpretation, intonation,
   job, keeping, legato, liturgy, management, maneuver, manipulation,
   masquerade, measure, mezzo staccato, mimesis, mimicking, mimicry,
   miming, mission accomplished, move, mummery, music-making,
   musical performance, musical program, observance, observation,
   occupation, office, opening, operancy, operation, ostentation,
   overacting, overproduction, overt act, pantomime, pantomiming,
   parlando, passage, patter, performing, perpetration, personation,
   personification, philharmonic, pianism, pizzicato, play,
   playacting, playing, pop concert, pops, popular concert, portrayal,
   posing, practice, premiere, presentation, presentment, proceeding,
   production, productiveness, program, program of music, projection,
   prom, promenade concert, realization, recital, religious ceremony,
   rendering, rendition, repercussion, representation, res gestae,
   respect, responsibility, retrospective, rite, rite de passage,
   rite of passage, ritual, rubato, running, satisfaction, scene,
   service, service of music, show, showing, slapstick, slur,
   solemnity, solemnization, spiccato, staccato, stage business,
   stage directions, stage presence, stage presentation, steering,
   step, stroke, stunt, success, swan song, symphony concert,
   taking a role, theatrical performance, thing, thing done, touch,
   tour de force, transaction, tryout, turn, undertaking, unfolding,
   unfoldment, unveiling, varnishing day, vernissage, work, working,
   workings, works



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PERFORMANCE. The act of doing something; the thing done is also called a
performance; as, Paul is exonerated from the obligation of his contract by
its performance.
     2. When it contract has been made by parol, which, under the statute of
frauds and perjuries, could not be enforced, because it was not in writing,
and the party seeking to avoid it, has received the whole or a part
performance of such agreement, he cannot afterwards avoid it; 14 John. 15;
S. C. 1 John. Ch. R. 273; and such part performance will enable the other
party to prove it aliunde. 1 Pet. C. C. R. 380; 1 Rand. R. 165; 1 Blackf. R.
58; 2 Day, R. 255; 1 Desaus. R. 350; 5 Day, R. 67; 1 Binn. R. 218; 3 Paige,
R. 545; 1 John. Ch. R. 131, 146. Vide Specific performance.