efficacy

noun ef·fi·ca·cy \ ˈe-fi-kə-sē \

Updated on: 22 May 2018

plural efficacies

: the power to produce an effect

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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

But the glimmers of efficacy were encouraging, says Jaume Pons in San Francisco, California, who was at that time head of protein engineering at Rinat, a spinoff of Genentech that specialized in antibodies to treat cancer.

— emily underwood, Science | AAAS, "Will antibodies finally put an end to migraines?," 18 May 2018
Experts are generally bullish on the efficacy of stem cells and their derivatives.

— kathleen hou, The Cut, "I Tried The ‘Penis Facial’," 16 May 2018
Even with hints of efficacy, there’s still no convincing proof cancer patients benefit more when experimental immune-boosting drugs are paired with immunotherapy blockbusters like Merck’s Keytruda and Bristol-Myers Squibb‘s Opdivo.

— adam feuerstein, STAT, "Combination cancer immunotherapies take center stage at ASCO’s annual meeting," 16 May 2018
With sanctions kicking-in between the next 90 to 180 days, all attention will be on the efficacy of American tools of financial pressure.

— behnam ben taleblu, Fortune, "Iran Could Benefit From the Brewing U.S.-Europe Nuclear Deal Dispute," 14 May 2018
Cleaner skin leads to better absorption of products, which leads to better efficacy, which leads to healthier skin.

— barret wertz, GQ, "The Best Anti-Pollution Skincare Treatments Every Guy Should Try This Summer," 14 May 2018
Aside from the efficacy, the school district’s denial that Cruz had any connection to the PROMISE program raises serious questions.

— dan sweeney, Sun-Sentinel.com, "What's the future for Broward's PROMISE program after news Nikolas Cruz was referred there?," 7 May 2018
On the other are questions of efficacy—nongovernmental databases, whether public or private, haven’t been vetted for use by law enforcement, even as they’re increasingly being used as crime-fighting tools.

— megan molteni, WIRED, "Detectives Cracked the Golden State Killer Case Using Genetics," 27 Apr. 2018
In light of the limited efficacy of surgical intervention, doctors have been tackling chronic back pain with pills.

— daisy yuhas, Scientific American, "Forget Pills and Surgery for Back Pain," 1 Oct. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'efficacy.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.