'efficacy' definitions:

Definition of 'efficacy'

(from WordNet)
noun
Capacity or power to produce a desired effect; "concern about the safety and efficacy of the vaccine" [syn: efficacy, efficaciousness] [ant: inefficaciousness, inefficacy]

Definition of 'efficacy'

From: GCIDE
  • efficacy \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: efficacy. [1913 Webster]
  • Syn: Virtue; force; energy; potency; efficiency. [1913 Webster] efficience

Words containing 'efficacy'