Efficacious
Pronunciation : Ef`fi*ca"cious
Part of Speech : a.
Etymology : [L. eficax, -acis, fr. efficere. See Effect, n.]
Definition : Defn: Possessing the quality of being effective; productive of, or powerful to produce, the effect intended; as, an efficacious law.
Syn. -- See Effectual. -- Ef`fi*ca"cious*ly, adv. -- Ef`fi*ca"cious*ness, n.
Source : Webster's Unabridged Dictionary, 1913