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
As such, optimistic claims about the efficacy of EdTech often mirror industry marketing narratives.
—
Dr. Timothy Scott, Hartford Courant, 31 Mar. 2026
In Hinduism and Buddhism, a mantra is a sacred utterance (syllable, word, or verse) that is considered to possess mystical or religious efficacy.
—Encyclopedia Britannica, 31 Mar. 2026
Earlier this week, pharmaceutical company Pfizer and its partner Valneva announced that an experimental Lyme disease vaccine showed more than 70% efficacy in late-stage clinical trials.
—Mary Kekatos, ABC News, 24 Mar. 2026
Finding passions, hobbies, community and values outside of family can help build self-worth and self-efficacy, Cole said.
—Rachel Hale, USA Today, 24 Mar. 2026
See All Example Sentences for efficacy
Dr. Timothy Scott, Hartford Courant, 31 Mar. 2026
In Hinduism and Buddhism, a mantra is a sacred utterance (syllable, word, or verse) that is considered to possess mystical or religious efficacy.
—Encyclopedia Britannica, 31 Mar. 2026
Earlier this week, pharmaceutical company Pfizer and its partner Valneva announced that an experimental Lyme disease vaccine showed more than 70% efficacy in late-stage clinical trials.
—Mary Kekatos, ABC News, 24 Mar. 2026
Finding passions, hobbies, community and values outside of family can help build self-worth and self-efficacy, Cole said.
—Rachel Hale, USA Today, 24 Mar. 2026
See All Example Sentences for efficacy
Recent Examples of Synonyms for efficacy
Noun
-
The bill proposes creating a comparative effectiveness review process for prescription drugs on the Medicaid formulary.—
James Hart,
Hartford Courant,
30 Mar. 2026
-
No injuries were reported among passengers or crew, underscoring the effectiveness of both onboard procedures and ground coordination.—
Aamir Khollam,
Interesting Engineering,
30 Mar. 2026
Noun
-
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
-
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 5 Apr. 2026.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
