Dictionary

efficacy

noun ef·fi·ca·cy \ˈe-fi-kə-sē\

: the power to produce a desired result or effect

plural ef·fi·ca·cies

Full Definition of EFFICACY

:  the power to produce an effect

Examples of EFFICACY

  1. <questioned the efficacy of the alarms in actually preventing auto theft>
  2. In the planner's view, Rumsfeld had two goals: to demonstrate the efficacy of precision bombing and to do the war on the cheap. —Seymour M. Hersh, New Yorker, 7 Apr. 2003

Origin of EFFICACY

(see efficacious)
First Known Use: 13th century

Browse

Next Word in the Dictionary: efficiencePrevious Word in the Dictionary: efficacityAll Words Near: efficacy
July 01, 2015
precarious Hear it
not certain, secure, or steady
Take a 3-minute break and test your skills!
How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears