EFFICACY Synonyms: 22 Similar and Opposite Words

efficacy

noun

ˈe-fi-kə-sē

Definition of efficacy

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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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 The idea is to meld the efficacy of prescription skin care with the look and feel of luxury skin care. — Kathryn Hopkins, Footwear News, 28 Aug. 2026 Political and security fractures will further reduce the efficacy of air defense networks. — Dina Esfandiary, Foreign Affairs, 27 Aug. 2026 Kennedy has a history of casting doubts on vaccines and spreading misleading claims about their safety and efficacy. — Stephanie Stahl, CBS News, 27 Aug. 2026 Without needing to establish safety or efficacy, researchers can skip ahead to trials testing their broader potential. — Mike McRae 26, New Atlas, 26 Aug. 2026 See All Example Sentences for efficacy

Recent Examples of Synonyms for efficacy

Noun

Calcium and vitamin D are often supplemented together for bone health, but research shows mixed results on their effectiveness in improving bone mineral density or reducing fracture risk.

— Jennifer Lefton, Verywell Health, 3 Sep. 2026
Milwaukee police officials have stood by the technology's effectiveness, despite months of criticism and two officers facing criminal charges for misuse of the system.

— David Clarey, jsonline.com, 3 Sep. 2026

Definition of effectiveness

Noun

This approach is intended to combine the efficiency and speed of wheeled movement with the obstacle-clearing capabilities associated with legged robots.

— Jijo Malayil, Interesting Engineering, 7 Sep. 2026
If Taron Johnson and the secondary hold up against complex passing schemes, the unit should take a noticeable leap in efficiency.

— David Troy OutKick, FOXNews.com, 6 Sep. 2026

Definition of efficiency

Browse Nearby Words

efficacity

efficacy

efficiency

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“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 10 Sep. 2026.

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Synonyms of efficacy

noun

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