Synonyms of efficacy

efficacy

noun

ˈe-fi-kə-sē 

as in effectiveness

the power to produce a desired result

questioned the efficacy of the alarms in actually preventing auto theft

Synonyms & Similar Words

• effectiveness
• efficaciousness
• efficiency
• productiveness
• ability
• efficacity
• effectualness
• capability
• edge
• strength
• potency
• capacity
• puissance

Antonyms & Near Antonyms

• ineffectiveness
• inefficiency
• inability
• inadequacy
• ineffectuality
• ineffectualness
• incompetence
• incompetency
• inadequateness

Example Sentences

Recent Examples of efficacy

For Liberty, that means stock holding, replenishment, product efficacy, customer loyalty and whether momentum extends beyond a single hero product. — Rhea Cartwright, Vogue, 2 Oct. 2026

With efficacy and affordability top of mind, Skin Union’s product boast ph-balancing, and filler-free formulas suitable for all skin types, and all under $30. — Kaleigh Werner, Footwear News, 1 Oct. 2026

Sarah Thompson, president of the Faculty Association of California Community Colleges, drew attention to the importance of recognizing AI’s ability to simultaneously facilitate education efficacy while impeding other forms of learning. — Tarini Mehta, Sacbee.com, 28 Sep. 2026

Until her mid-80s, Georgeanna continued to work on improving methods of IVF therapy to further ensure its safety and efficacy, according to the Jones Foundation for Reproductive Medicine, which was named after the couple. — David Chiu, PEOPLE, 24 Sep. 2026