The Collaborative International Dictionary of English v.0.48:

Manipulation \Ma*nip`u*la"tion\, n. [Cf. F. manipulation.]
   1. The act or process of manipulating, or the state of being
      manipulated; the act of handling work by hand; use of the
      hands, in an artistic or skillful manner, in science or
      art.
      [1913 Webster]

            Manipulation is to the chemist like the external
            senses to the mind. --Whewell.
      [1913 Webster]

   2. The use of the hands in mesmeric operations.
      [1913 Webster]

   3. Artful management; as, the manipulation of political
      bodies; sometimes, a management or treatment for purposes
      of deception or fraud.
      [1913 Webster]

WordNet (r) 3.0 (2006):

manipulation
    n 1: exerting shrewd or devious influence especially for one's
         own advantage; "his manipulation of his friends was
         scandalous" [syn: manipulation, use]
    2: the action of touching with the hands (or the skillful use of
       the hands) or by the use of mechanical means [syn:
       handling, manipulation]

Moby Thesaurus II by Grady Ward, 1.0:

133 Moby Thesaurus words for "manipulation":
   accounting, action, agency, anal intercourse, analysis, artifice,
   authority, autoeroticism, automatic electronic navigation,
   bear raid, behind-the-scenes influence, bestiality, braking,
   buggery, bull raid, cabal, caressing, collusion, command,
   complicity, complot, computation, conduct, confederacy, connivance,
   conspiracy, contrivance, contriving, control, coordination, corner,
   corner in, counterplot, covin, cunnilingus, deep-laid plot,
   devices, direction, driving, employment, engineering, execution,
   exercise, expedients, exploitation, fact distribution, feeling,
   fellatio, fellation, finagling, finesse, fingering, forecasts,
   frame-up, friction, frottage, functioning, game, governance,
   government, guidance, hand job, handling, husbandry, influence,
   inspection, intrigue, irrumation, lead, leading, little game,
   machination, management, managery, managing, maneuvering,
   maneuvers, masturbation, monopoly, nonlinear calibrations,
   occupation, onanism, operancy, operation, oral-genital stimulation,
   ordering, output measurement, palpation, pederasty, performance,
   performing, petting, pilotage, plot, plotting, political influence,
   practice, pressure, processing, raid, record keeping, regulation,
   responsibility, rigging, rubbing, running, scheme, schemery,
   scheming, self-abuse, sodomy, steerage, steering, stratagem,
   stroking, supersonic flow detection, tactical maneuvers, tactics,
   the conn, the helm, the wheel, touching, trick, underplot, using,
   utilization, wash sale, washing, web of intrigue, wire-pulling,
   work, working, workings