The Collaborative International Dictionary of English v.0.48:

Operate \Op"er*ate\, v. t.
   1. To produce, as an effect; to cause.
      [1913 Webster]

            The same cause would operate a diminution of the
            value of stock.                       --A. Hamilton.
      [1913 Webster]

   2. To put into, or to continue in, operation or activity; to
      work; as, to operate a machine.
      [1913 Webster] Operatic

The Collaborative International Dictionary of English v.0.48:

Operate \Op"er*ate\, v. i. [imp. & p. p. Operated; p. pr. &
   vb. n. Operating.] [L. operatus, p. p. of operari to work,
   fr. opus, operis, work, labor; akin to Skr. apas, and also to
   G. ["u]ben to exercise, OHG. uoben, Icel. [ae]fa. Cf.
   Inure, Maneuver, Ure.]
   1. To perform a work or labor; to exert power or strength,
      physical or mechanical; to act.
      [1913 Webster]

   2. To produce an appropriate physical effect; to issue in the
      result designed by nature; especially (Med.), to take
      appropriate effect on the human system.
      [1913 Webster]

   3. To act or produce effect on the mind; to exert moral power
      or influence.
      [1913 Webster]

            The virtues of private persons operate but on a few.
                                                  --Atterbury.
      [1913 Webster]

            A plain, convincing reason operates on the mind both
            of a learned and ignorant hearer as long as they
            live.                                 --Swift.
      [1913 Webster]

   4. (Surg.) To perform some manual act upon a human body in a
      methodical manner, and usually with instruments, with a
      view to restore soundness or health, as in amputation,
      lithotomy, etc.
      [1913 Webster]

   5. To deal in stocks or any commodity with a view to
      speculative profits. [Brokers' Cant]
      [1913 Webster]

WordNet (r) 3.0 (2006):

operate
    v 1: direct or control; projects, businesses, etc.; "She is
         running a relief operation in the Sudan" [syn: operate,
         run]
    2: perform as expected when applied; "The washing machine won't
       go unless it's plugged in"; "Does this old car still run
       well?"; "This old radio doesn't work anymore" [syn:
       function, work, operate, go, run] [ant:
       malfunction, misfunction]
    3: handle and cause to function; "do not operate machinery after
       imbibing alcohol"; "control the lever" [syn: operate,
       control]
    4: perform a movement in military or naval tactics in order to
       secure an advantage in attack or defense [syn: manoeuver,
       maneuver, manoeuvre, operate]
    5: happen; "What is going on in the minds of the people?"
    6: keep engaged; "engaged the gears" [syn: engage, mesh,
       lock, operate] [ant: disengage, withdraw]
    7: perform surgery on; "The doctors operated on the patient but
       failed to save his life" [syn: operate on, operate]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "operate":
   act, angle, be caught short, be effective, be in action,
   be responsible for, be short, behave, belong, brew, bucket,
   bucketshop, cabal, carry on, carry out, carry through,
   chart a course, collude, complot, concoct, cond, conduct, conn,
   connive, conspire, control, cook up, countermine, counterplot,
   coxswain, cut, deal with, deposit margin, direct, do with, drive,
   employ, engineer, exercise, exert, finagle, finesse, frame,
   frame up, function, go, go long, guide, handle, hatch,
   hatch a plot, hatch up, have effect, have free play, have play,
   have the conn, helm, hold on, intrigue, keep, lay a plot,
   machinate, make, make a killing, make a scoop, make go,
   make use of, manage, maneuver, manipulate, margin up, militate,
   miss the market, move, navigate, open up, ordain,
   overstay the market, percolate, perform, perform on, perk, pilot,
   play, play the market, plot, plunge, ply, practice, proceed,
   pyramid, react, rig, run, scalp, scheme, scoop the market, see to,
   serve, shape a course, speculate, stag, stag the market, steer,
   take, take a flier, take care of, take effect, tick,
   trade on margin, use, utilize, venture, wangle, wield, work