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

The Pentagon has rolled out formal guidance for mandatory testosterone testing for male service members 30 and older, a policy that leaves out women for now and faces questions from medical experts about the need and efficacy of such a program. — ABC News, 18 Sep. 2026

This construct measures four developable capacities—hope, efficacy, resilience and optimism, collectively known as HERO. — Expert Panel®, Forbes.com, 18 Sep. 2026

However, the insights and experiences of dozens of sources highlight that some individuals and clubs are finding ways to game the system, raising questions over the efficacy of the existing rules and the five-step process. — Jordan Campbell, New York Times, 14 Sep. 2026

Critically, Pachocki wrote that one of the primary tools OpenAI and other AI companies have used to verify if AI models are following user intentions and check for misbehavior is losing its efficacy. — Jeremy Kahn, Fortune, 8 Sep. 2026