—adj.
1 having a definite or desired effect.
2 powerful in effect; impressive.
3 a actual; existing in fact rather than officially or theoretically (took effective control in their absence). b actually usable; realizable; equivalent in its effect (effective money; effective demand).
4 coming into operation (effective as from 1 May).
5 (of manpower) fit for work or service.
—n. a soldier available for service.
Derivatives:
effectively adv. effectiveness n.
Etymology: ME f. L effectivus (as EFFECT)
Useful english dictionary. 2012.