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]

The Collaborative International Dictionary of English v.0.48:

operating \operating\ adj.
   1. pr. p. of operate; as, the operating conditions of the
      oxidation pond.
      [WordNet 1.5]

   2. having an effect or influence.

   Syn: at work(predicate), in operation, operant.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

operating
    adj 1: involved in a kind of operation; "the operating
           conditions of the oxidation pond"
    2: being in effect or operation; "de facto apartheid is still
       operational even in the `new' African nations"- Leslie Marmon
       Silko; "bus service is in operation during the emergency";
       "the company had several operating divisions" [syn:
       operational, in operation(p), operating(a)]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "operating":
   acting, active, at work, behavioral, functional, functioning,
   going, going on, in exercise, in force, in hand, in operation,
   in play, in practice, in process, in the works, inaction, on foot,
   on the fire, ongoing, operational, performing, practicing, running,
   serving, working



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

operating

   1. operating system.

   2. operator.