operant

adj

1. That operates to produce an effect.

   “thy most operant poison”

   “I tell you frankly, if Paul Aubry is guilty I hope is convicted and punished; but if one of the others is guilty I hope he—or she—is punished, and if I knew anything operant to that end I certainly would not withhold it.”

noun

1. An operative person or thing.
2. Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment.