as in effectiveness
the power to produce a desired result
questioned the efficacy of the alarms in actually preventing auto theft
Synonyms & Similar Words
Relevance
Antonyms & Near Antonyms
Example Sentences
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Recent Examples of efficacy
But 11% of the patients on the highest dose discontinued due to adverse events, and when analyzing all patients, including those who discontinued, the efficacy was 25%.
—
Ed Silverman, STAT, 21 May 2026
But some gardeners are starting to question the efficacy of plastic weed barriers.
—David Beaulieu, The Spruce, 21 May 2026
This suggests doctors are willing to trade weight-loss efficacy, where Wegovy may have a slight edge, in favor of ease of use.
—Jeff Marks,paulina Likos, CNBC, 19 May 2026
However, much more testing is required to determine its efficacy and safety compared to other currently available sunscreens.
—Devika Rao, TheWeek, 18 May 2026
See All Example Sentences for efficacy
Ed Silverman, STAT, 21 May 2026
But some gardeners are starting to question the efficacy of plastic weed barriers.
—David Beaulieu, The Spruce, 21 May 2026
This suggests doctors are willing to trade weight-loss efficacy, where Wegovy may have a slight edge, in favor of ease of use.
—Jeff Marks,paulina Likos, CNBC, 19 May 2026
However, much more testing is required to determine its efficacy and safety compared to other currently available sunscreens.
—Devika Rao, TheWeek, 18 May 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
-
Only 30% of the studies, or 23/77, even attempted to test for mask effectiveness.—
Ian Miller OutKick,
FOXNews.com,
1 June 2026
-
This in turn depends on their preferences for what is and is not covered based on many different factors, including products’ clinical- and cost-effectiveness, budgetary impact and other considerations.—
Joshua P. Cohen,
Forbes.com,
1 June 2026
Noun
-
Grutsch said the renovation builds in efficiency for each specific unit and purpose.—
Elliot Mann,
Twin Cities,
29 May 2026
-
One of its findings was that those countries that prioritized transitioning to clean energy alongside electrification and efficiency saved some $260 billion in fossil fuel import costs last year, with savings expected to grow substantially this year.—
Justin Worland,
Time,
29 May 2026
Cite this Entry
“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 4 Jun. 2026.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
