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

Now the technique has become mainstream as attackers reap its simplicity and effectiveness in infecting users of PCs and Macs alike.

— Dan Goodin, ArsTechnica, 11 Sep. 2026
The chaotic, violence-laden sequence is but the first of many in a film that aspires to classic Hollywood action movie status but reduces its effectiveness through overkill of both the literal and figurative kind.

— Frank Scheck, HollywoodReporter, 10 Sep. 2026

Definition of effectiveness

Noun

That means more scrutiny on gross margins, infrastructure efficiency, how costs scale relative to revenue, and your serviceable debt capacity.

— Denada Ramnishta, Forbes.com, 14 Sep. 2026
Age-band extension, category breadth, product sophistication and supply-chain efficiency are becoming the new battlegrounds.

— Li Jun, Footwear News, 14 Sep. 2026

Definition of efficiency

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efficacity

efficacy

efficiency

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“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 16 Sep. 2026.

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Synonyms of efficacy

noun

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