Ef′fi‐ca″cious (?), a. [L. eficax, -acis, fr. efficere. See Effect, n.] 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.