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
The move is popular, with polls finding 74% support, although the evidence for both the mental health impacts of social media and the efficacy of bans is disputed.
—
Tom Chivers, semafor.com, 15 June 2026
Stanford says human clinical trials are expected in the near future, but every new drug must clear safety trials, dosing studies and efficacy trials before approval.
—Allison Palmer
updated June 13, Kansas City Star, 13 June 2026
During the coronavirus pandemic, Sarah watched policies that seemed designed for urbanites arrive in her rural town without the consent of residents or evidence of their local efficacy.
—Scott Warren, The Atlantic, 13 June 2026
Safety and Stability Properties Between various countries’ regulatory approval and real-world use, bemotrizinol has some of the most robust safety and efficacy testing among sunscreen filters.
—Lauren J. Young, Scientific American, 9 June 2026
See All Example Sentences for efficacy
Tom Chivers, semafor.com, 15 June 2026
Stanford says human clinical trials are expected in the near future, but every new drug must clear safety trials, dosing studies and efficacy trials before approval.
—Allison Palmer
updated June 13, Kansas City Star, 13 June 2026
During the coronavirus pandemic, Sarah watched policies that seemed designed for urbanites arrive in her rural town without the consent of residents or evidence of their local efficacy.
—Scott Warren, The Atlantic, 13 June 2026
Safety and Stability Properties Between various countries’ regulatory approval and real-world use, bemotrizinol has some of the most robust safety and efficacy testing among sunscreen filters.
—Lauren J. Young, Scientific American, 9 June 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
-
The potential pitfall of that is diluting Walker’s effectiveness at his primary position.—
Josh Kendall,
New York Times,
16 June 2026
-
The plan was met with mixed reaction, with some praising Starmer for taking action and others questioning the effectiveness of a blanket ban.—
ABC News,
ABC News,
15 June 2026
Noun
-
If successful, the technology could provide continuous, high-efficiency clean energy, transforming the global power supply.—
Chris Young,
Interesting Engineering,
19 June 2026
-
Across southeast Asia, governments have raced to facilitate deployment of electric vehicles and other fuel-efficiency measures.—
Justin Worland,
Time,
19 June 2026
Cite this Entry
“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 22 Jun. 2026.
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