The Collaborative International Dictionary of English v.0.48:

Operator \Op"er*a`tor\, n. [L.]
   1. One who, or that which, operates or produces an effect.
      [1913 Webster]

   2. (Surg.) One who performs some act upon the human body by
      means of the hand, or with instruments.
      [1913 Webster]

   3. A dealer in stocks or any commodity for speculative
      purposes; a speculator. [Brokers' Cant]
      [1913 Webster]

   4. (Math.) The symbol that expresses the operation to be
      performed; -- called also facient.
      [1913 Webster]

   5. A person who operates a telephone switchboard.
      [PJC]

   6. A person who schemes and maneuvers adroitly or deviously
      to achieve his/her purposes.
      [PJC]

WordNet (r) 3.0 (2006):

operator
    n 1: (mathematics) a symbol or function representing a
         mathematical operation
    2: an agent that operates some apparatus or machine; "the
       operator of the switchboard" [syn: operator, manipulator]
    3: someone who owns or operates a business; "who is the operator
       of this franchise?"
    4: a shrewd or unscrupulous person who knows how to circumvent
       difficulties [syn: hustler, wheeler dealer, operator]
    5: a speculator who trades aggressively on stock or commodity
       markets

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "operator":
   Machiavellian, PBX operator, activist, actor, administrator,
   adventurer, agent, architect, author, ball of fire, beaver,
   behind-the-scenes operator, big operator, big wheel,
   big-time operator, bustler, busy bee, central, coconspirator,
   conductor, conniver, conspirator, conspirer, counterplotter,
   creator, director, doer, driver, eager beaver, eminence grise,
   engineer, enthusiast, executant, executor, executrix, exploiter,
   fabricator, faker, finagler, fraud, functionary, gamesman,
   go-getter, gray eminence, gunslinger, handler, human dynamo,
   hustler, intrigant, intriguer, kingmaker, lame duck, live wire,
   logroller, long distance, machinator, maker, man of action,
   man of deeds, manager, maneuverer, manipulator, margin purchaser,
   medium, militant, mover, new broom, operant, operative,
   operative surgeon, opportunist, performer, perpetrator, pilot,
   plotter, plunger, political activist, pork-barrel politician,
   powerhouse, practitioner, prime mover, producer, runner, sawbones,
   scalper, schemer, smart operator, smoothie, speculator, stag,
   steersman, strategist, subject, superintendent, supervisor,
   surgeon, switchboard operator, take-charge guy, telephone operator,
   telephonist, wheeler-dealer, winner, wire-puller, wise guy,
   worker



The Free On-line Dictionary of Computing (30 December 2018):

operator

    A symbol used as a function, with infix
   syntax if it has two arguments (e.g. "+") or prefix syntax if
   it has only one (e.g. Boolean NOT).  Many languages use
   operators for built-in functions such as arithmetic and logic.

   (1995-04-30)