Webster's Revised Unabridged Dictionary (1913 + 1828)

Displaying 1 result(s) from the 1913 edition:
Efficacy (Page: 472)

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