Operative

1. Having the power of acting; hence, exerting force, physical or moral; active in the production of effects; as, an operative motive.
2. A skilled worker; an artisan; esp., one who operates a machine in a mill or manufactory.
3. Producing the appropriate or designed effect; efficacious; as, an operative dose, rule, or penalty.
4. Based upon, or consisting of, an operation or operations; as, operative surgery.