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 metal shutters and advanced outdoor sprinkler system are the flashiest parts of Tavangarian’s home hardening project, and the efficacy of these adaptations is still up for debate.
—
Los Angeles Times, 2 Mar. 2026
Consider using heavy-duty aluminum foil for recipes requiring higher oven temperatures, like 450 degrees, to ensure safety and efficacy.
—Kait Hanson, Southern Living, 28 Feb. 2026
This is especially true of detergent formulas that rely on enzymes for eliminating stains, as enzymes lose efficacy over time.
—Jolie Kerr, Better Homes & Gardens, 27 Feb. 2026
Claude also happens to already have considerable military applications, such as synthesizing huge amounts of intelligence and information and boosting the efficacy of government hackers.
—Idrees Kahloon, The Atlantic, 26 Feb. 2026
See All Example Sentences for efficacy
Los Angeles Times, 2 Mar. 2026
Consider using heavy-duty aluminum foil for recipes requiring higher oven temperatures, like 450 degrees, to ensure safety and efficacy.
—Kait Hanson, Southern Living, 28 Feb. 2026
This is especially true of detergent formulas that rely on enzymes for eliminating stains, as enzymes lose efficacy over time.
—Jolie Kerr, Better Homes & Gardens, 27 Feb. 2026
Claude also happens to already have considerable military applications, such as synthesizing huge amounts of intelligence and information and boosting the efficacy of government hackers.
—Idrees Kahloon, The Atlantic, 26 Feb. 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
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These have questionable or no effectiveness, says Owen.—
Arricca Elin SanSone,
Southern Living,
9 Mar. 2026
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This is an ideal solution for technically adept web admins who prioritize cost-effectiveness, absolute control, and performance.—
Gabriel Zamora,
PC Magazine,
8 Mar. 2026
Noun
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Charging the future faster than ever BYD is introducing the 2nd Generation Blade Battery and FLASH Charging Technology, pushing the boundaries of safety, efficiency and performance.—
Sujita Sinha,
Interesting Engineering,
6 Mar. 2026
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There are good ideas in the document, from expanding EV charging stations to improving water efficiency and reducing solid waste.—
The Editorial Board,
Oc Register,
6 Mar. 2026
Cite this Entry
“Efficacy.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacy. Accessed 11 Mar. 2026.
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