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. 2003Vaccines exist, but their efficacy against aerosolized plague is unknown.—Sharon Begley et al., Newsweek, 8 Oct. 2001… efficacy does not have to be demonstrated before homeopathic products are marketed.—Alison Abbott et al., Nature, 26 Sept. 1996
questioned the efficacy of the alarms in actually preventing auto theft
Recent Examples on the WebAs this procedure’s approval rating grows so too does evidence supporting its efficacy.—Jolene Edgar, Allure, 1 May 2024 But the efficacy of the voluntary pledge remains to be seen.—Eric Geller, WIRED, 1 May 2024 See all Example Sentences for efficacy
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'efficacy.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
Etymology
borrowed from Latin efficācia, from efficāc-, efficāx "capable of fulfilling a function, efficacious" + -ia-y entry 2
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