(1):

(a.) Having the power of acting; hence, exerting force, physical or moral; active in the production of effects; as, an operative motive.

(2):

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

(3):

(n.) A skilled worker; an artisan; esp., one who operates a machine in a mill or manufactory.

(4):

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