Efficacy

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [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

From WordNet (r) 2.0 [wn]:

  efficacy
       n : capacity or power to produce a desired effect; "concern
           about the safety and efficacy of the vaccine" [syn: {efficaciousness}]
           [ant: {inefficacy}]