Akademik

operative
adj. & n.
—adj.
1 in operation; having effect.
2 having the principal relevance ('may' is the operative word).
3 of or by surgery.
4 Law expressing an intent to perform a transaction.
—n.
1 a worker, esp. a skilled one.
2 US a private detective.
Derivatives:
operatively adv. operativeness n.
Etymology: LL operativus f. L (as OPERATE)

Useful english dictionary. 2012.