Category:Efficacy

Ef"fi*ca*cy, n. Etym: [L. efficacia, fr. efficax. See Efficacious.]

Defn: Power to produce effects; operation or energy of an agent or force; production of the effect intended; as, the efficacy of medicine in counteracting disease; the efficacy of prayer. "Of noxious efficacy." Milton.

Syn. -- Virtue; force; energy; potency; efficiency.