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 first in-human clinical trial will assess the drug's safety profile, hopefully providing a green light for further efficacy studies. — New Atlas, 2 July 2026

Belief in the efficacy of bloodletting was well-established and undisputed until well into the 1800s. — Katherine Ott, The Conversation, 2 July 2026

Harvard Health has published a critical take on Apollo Neuro, and Medscape has cautioned about at-home vagus nerve stimulation devices, warning of uncertain efficacy and safety. — Samantha Agate, Kansas City Star, 2 July 2026

Its technology involved advanced tissue models and microfluidics testing systems for safety and efficacy studies. — Thomas Lim, Forbes.com, 2 July 2026