Ef"fi*ca*cy (?), n. [L. efficacia, fr. efficax. See Efficacious.]

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."


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


© Webster 1913.

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