Source : Webster's Revised Unabridged Dictionary (1913)

Operative \Op"er*a*tive\, a. [Cf.L. operativus, F. op['e]ratif.]
   1. Having the power of acting; hence, exerting force,
      physical or moral; active in the production of effects;
      as, an operative motive.

            It holds in all operative principles. --South.

   2. Producing the appropriate or designed effect; efficacious;
      as, an operative dose, rule, or penalty.

   3. (Surg.) Based upon, or consisting of, an operation or
      operations; as, operative surgery.

Operative \Op"er*a*tive\, n.
   A skilled worker; an artisan; esp., one who operates a
   machine in a mill or manufactory.

Source : WordNet®

operative
     n 1: a person secretly employed in espionage for a government
          [syn: {secret agent}, {intelligence officer}, {intelligence
          agent}]
     2: someone who can be employed as a detective to collect
        information [syn: {private detective}, {PI}, {private eye},
         {private investigator}, {shamus}, {sherlock}]

operative
     adj 1: being in force or having or exerting force; "operative
            regulations"; "the major tendencies operative in the
            American political system" [ant: {inoperative}]
     2: of or relating to a surgical operation; "operative surgery"
     3: relating to or requiring or amenable to treatment by surgery
        especially as opposed to medicine; "a surgical appendix";
        "a surgical procedure"; "operative dentistry" [syn: {surgical}]
        [ant: {medical}]
     4: effective; producing a desired effect; "the operative word"
        [syn: {key}]
     5: (of e.g. a machine) performing or capable of performing; "in
        running (or working) order"; "a functional set of brakes"
        [syn: {running(a)}, {functional}, {working(a)}]