adj. & n.
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. effectively adv. effectiveness n.
[ ME f. L effectivus (as EFFECT) ]