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 clinical trials will test two separate drugs, MBP-134 and remdesivir, for efficacy in treating the Bundibugyo Ebola virus. — Omer Awan, Forbes.com, 7 July 2026

Neuropeptides Neuropeptides, short for neurotransmitter-inhibiting peptides, are the neurocosmetics with the most scientific backing to anchor their efficacy. — Deanna Pai, Vogue, 6 July 2026

However, as the industry innovates with newer products such as high alcohol content beer or ready-to-drink cocktails, the efficacy of the categorical system continues to break down. — Adam Hoffer, Chicago Tribune, 5 July 2026

Program planning needs to take into account the fun factor without losing efficacy. — Matt Parrott, Arkansas Online, 5 July 2026