Definition of efficacy
: the power to produce an effect
Examples of efficacy in a sentence
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
Vaccines 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 of efficacy from the web
As much as his efficacy in front of the goal, and the characteristic imagination in his play, his undimmed appetite for the battle has impressed.
Data such as this supports the belief in and bolsters the efficacy of familial searching to produce valuable leads.
David Plouffe, who helped lead Mr. Obama’s 2008 effort, said presidential media was a long game, and its efficacy could truly be judged only in November.
The article in which the findings were published focuses on the efficacy of a new sensor developed to test for formaldehyde fumes.
Any deception regarding the efficacy of its testing, especially if consumers were misled, could lead to charges under the federal mail and wire fraud statutes.
Hoping for any sort of fallout from Trump's advocacy for the efficacy of torture seems unlikely for the candidate who, thus far, appears impervious to outside attacks.
But the efficacy of strategic bombing is only half the question.
Because experience witnesseth that eccelsiastical establishments, instead of maintaining the purity and efficacy of Religion, have had a contrary operation.
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Origin and Etymology of efficacy
First Known Use: 13th century
EFFICACY Defined for English Language Learners
Definition of efficacy for English Language Learners
: the power to produce a desired result or effect
Seen and Heard
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