Op"er*a*tive (?), a. [Cf.L. operativus, F. opératif.] 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.

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.

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

• That which is important or effectual.
       The operative word in the phrase "last chance" is "last".
  
• Functional, in working order.
  
• A spy.