The Collaborative International Dictionary of English v.0.48:

Act \Act\, v. t. [imp. & p. p. Acted; p. pr. & vb. n.
   Acting.] [L. actus, p. p. of agere to drive, lead, do; but
   influenced by E. act, n.]
   1. To move to action; to actuate; to animate. [Obs.]
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            Self-love, the spring of motion, acts the soul.
                                                  --Pope.
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   2. To perform; to execute; to do. [Archaic]
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            That we act our temporal affairs with a desire no
            greater than our necessity.           --Jer. Taylor.
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            Industry doth beget by producing good habits, and
            facility of acting things expedient for us to do.
                                                  --Barrow.
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            Uplifted hands that at convenient times
            Could act extortion and the worst of crimes.
                                                  --Cowper.
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   3. To perform, as an actor; to represent dramatically on the
      stage.
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   4. To assume the office or character of; to play; to
      personate; as, to act the hero.
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   5. To feign or counterfeit; to simulate.
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            With acted fear the villain thus pursued. --Dryden.
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   To act a part, to sustain the part of one of the characters
      in a play; hence, to simulate; to dissemble.

   To act the part of, to take the character of; to fulfill
      the duties of.
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The Collaborative International Dictionary of English v.0.48:

Acting \Act"ing\, a.
   1. Operating in any way.
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   2. Doing duty for another; officiating; as, an acting
      superintendent.
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WordNet (r) 3.0 (2006):

acting
    adj 1: serving temporarily especially as a substitute; "the
           acting president"
    n 1: the performance of a part or role in a drama [syn:
         acting, playing, playacting, performing]

Moby Thesaurus II by Grady Ward, 1.0:

143 Moby Thesaurus words for "acting":
   act, action, active, activism, activity, ad interim, affectation,
   aping, appearance, at work, attitudinizing, behavior, behavioral,
   bluff, bluffing, buffoonery, business, characterization, cheating,
   color, coloring, deception, delusion, deputative, deputy, disguise,
   dissemblance, dissembling, dissimulation, doing, dumb show,
   embodiment, employment, enacting, enactment, exercise, facade,
   face, fakery, faking, false air, false front, false show, falsity,
   feigning, feint, four-flushing, fraud, front, function, functional,
   functioning, gag, gilt, gloss, going, going on, ham, hammy acting,
   hoke, hokum, humbug, humbuggery, imitation, impersonation,
   imposture, in exercise, in force, in hand, in operation, in play,
   in practice, in process, in the works, inaction, incarnation,
   interim, masquerade, meretriciousness, mimesis, mimicking, mimicry,
   miming, movements, mummery, occupation, on foot, on the fire,
   ongoing, operating, operation, operational, operations,
   ostentation, outward show, overacting, pantomime, pantomiming,
   patter, performance, performing, personation, personification,
   play, playacting, playing, portrayal, pose, posing, posture,
   practice, practicing, praxis, pretense, pretension, pretext,
   pro tem, pro tempore, projection, representation, representative,
   running, seeming, semblance, serving, sham, show, simulacrum,
   simulation, slapstick, speciousness, stage business,
   stage directions, stage presence, stunt, supply, swing,
   taking a role, varnish, window dressing, work, working, workings