efficacy

ef·fi·ca·cy

noun \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
3. Vaccines exist, but their efficacy against aerosolized plague is unknown. —Sharon Begley et al., Newsweek, 8 Oct. 2001
4. … efficacy does not have to be demonstrated before homeopathic products are marketed. —Alison Abbott et al., Nature, 26 Sept. 1996

Origin of EFFICACY

(see efficacious)

First Known Use: 13th century

Related to EFFICACY

Synonyms

edge, effectiveness, effectualness, efficaciousness, efficacity, efficiency, productiveness

Antonyms

ineffectiveness, ineffectuality, ineffectualness, inefficiency

Related Words

ability, capability, capacity; potency, puissance, strength

Near Antonyms

inability, inadequacy, inadequateness, incompetence, incompetency