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
Mainstream public health experts warn that peptides haven’t been sufficiently studied for efficacy or potential side effects like cancer risk.
—
Theresa Gaffney, STAT, 6 Apr. 2026
Data and metrics are two common methods for evaluating performance and efficacy in a variety of industries, but certainly in marketing and other communications fields.
—William Jones, Miami Herald, 3 Apr. 2026
They’re not allowed to look at efficacy.
—Anjeanette Damon, ProPublica, 3 Apr. 2026
Other ingredients can alter the moisturizer's efficacy and benefits.
—John Monaco, InStyle, 1 Apr. 2026
See All Example Sentences for efficacy
Theresa Gaffney, STAT, 6 Apr. 2026
Data and metrics are two common methods for evaluating performance and efficacy in a variety of industries, but certainly in marketing and other communications fields.
—William Jones, Miami Herald, 3 Apr. 2026
They’re not allowed to look at efficacy.
—Anjeanette Damon, ProPublica, 3 Apr. 2026
Other ingredients can alter the moisturizer's efficacy and benefits.
—John Monaco, InStyle, 1 Apr. 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
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The brief casts doubt on the agency’s effectiveness due to a lack of partnerships between the FWA, local authorities, unions, enforcement agencies and community organizations.—
Angela Velasquez,
Footwear News,
6 Apr. 2026
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But the Iran war has also highlighted the effectiveness of low-cost weapons.—
Jason Ma,
Fortune,
6 Apr. 2026
Noun
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Denver metro test drive loop My drives with the Prius covered much of the South Denver metro area, including stretches of C-470 and E-470, where steady highway cruising allowed the hybrid system to show off its efficiency.—
Sponsored Content,
Denver Post,
4 Apr. 2026
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Beginning with the loss at Michigan State, the Illini lost four out of their next six, the defense giving up 89 points per game and tracking its worst efficiency numbers of the season on KenPom.—
Dana O’Neil,
CNN Money,
3 Apr. 2026
Cite this Entry
“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 10 Apr. 2026.
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