as in effectiveness
the power to produce a desired result
questioned the efficacy of the alarms in actually preventing auto theft
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Recent Examples of efficacy
In one study, the perception by users that social media is addictive, due mainly to believing news media narratives, actually reduces self-efficacy and makes overuse more likely.
—
William Proctor, The Orlando Sentinel, 11 Apr. 2026
So much of the attention surrounding GLP-1s has been on their remarkable efficacy at shedding weight—and the search for drugs that are even better.
—Nicholas Florko, The Atlantic, 11 Apr. 2026
For instance, industry has distinct knowledge about AI’s emergent capabilities and risks, the efficacy of evaluations, and innovations in model training and alignment.
—Morgan Chalfant, semafor.com, 10 Apr. 2026
These claims contradict decades of scientific evidence that demonstrates the safety and efficacy of combination vaccines.
—Kar-Hai Chu, The Conversation, 10 Apr. 2026
See All Example Sentences for efficacy
William Proctor, The Orlando Sentinel, 11 Apr. 2026
So much of the attention surrounding GLP-1s has been on their remarkable efficacy at shedding weight—and the search for drugs that are even better.
—Nicholas Florko, The Atlantic, 11 Apr. 2026
For instance, industry has distinct knowledge about AI’s emergent capabilities and risks, the efficacy of evaluations, and innovations in model training and alignment.
—Morgan Chalfant, semafor.com, 10 Apr. 2026
These claims contradict decades of scientific evidence that demonstrates the safety and efficacy of combination vaccines.
—Kar-Hai Chu, The Conversation, 10 Apr. 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
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The device uses heat therapy combined with SonicGlow to activate your skin care by assisting with deeper absorption and effectiveness.—
Tory Johnson,
ABC News,
13 Apr. 2026
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But this loss of horsepower and expertise has come at the cost of her own effectiveness in the role—if, that is, effectiveness is really the goal to begin with.—
Quinta Jurecic,
The Atlantic,
13 Apr. 2026
Noun
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The parade route itself has been shortened slightly to improve efficiency.—
Madisen Keavy,
CBS News,
18 Apr. 2026
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Researchers at the Ningbo Institute of Industrial Technology in China have turned to diamond-copper coatings to improve the cooling efficiency of artificial intelligence (AI) data centers.—
Ameya Paleja,
Interesting Engineering,
17 Apr. 2026
Cite this Entry
“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 20 Apr. 2026.
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