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

However, effective delivery remains a critical challenge; Junho Jung stresses that topical applications often lack the efficacy of clinical injections, as ingredient stability and form are crucial for skin absorption. — Laia Farran Graves, Forbes.com, 12 Aug. 2026

Even before Bridge, the introduction of the current generation of GLP-1 medications for weight loss has brought prescribing challenges as profound as the medications’ remarkable efficacy. — Jeffrey Millstein, STAT, 11 Aug. 2026

The Japanese yen has already erased half the gains that came from the historic US-Japan currency intervention, raising questions over the efficacy of the maneuver and whether more currency moves may be needed to stop the yen’s slide. — Shelly Banjo, semafor.com, 10 Aug. 2026

But without a significant body of research proving these tools’ efficacy – and some studies showing harm – a growing number of experts are worried that children have become the guinea pigs of the next Big Tech experiment. — Aaron Glantz, Christian Science Monitor, 7 Aug. 2026