Synonym Chooser

How does the adjective efficacious contrast with its synonyms?

Some common synonyms of efficacious are effective, effectual, and efficient. While all these words mean "producing or capable of producing a result," efficacious suggests possession of a special quality or virtue that gives effective power.

a detergent that is efficacious in removing grease

When is effective a more appropriate choice than efficacious?

In some situations, the words effective and efficacious are roughly equivalent. However, effective stresses the actual production of or the power to produce an effect.

an effective rebuttal

When would effectual be a good substitute for efficacious?

Although the words effectual and efficacious have much in common, effectual suggests the accomplishment of a desired result especially as viewed after the fact.

the measures to stop the pilfering proved effectual

When can efficient be used instead of efficacious?

While the synonyms efficient and efficacious are close in meaning, efficient suggests an acting or a potential for action or use in such a way as to avoid loss or waste of energy in effecting, producing, or functioning.

an efficient small car

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of efficacious These efficacious, natural ingredients include chamomile, California poppy, lemon verbena, linden, magnesium, rosemary and cardamom. Bianca Salonga, Forbes.com, 1 Apr. 2025 Thorne is also rigorously tested and has worked with independent researchers from places like Mayo Clinic and the National Institutes of Health, to ensure its products are high-performance, safe, and efficacious. Vogue, 30 Mar. 2025 Despite Chief Justice Warren formally writing the opinion to apply exclusively to education, its attack on segregation has—paradoxically—been most efficacious beyond that original context. Justin Driver, The Atlantic, 15 Mar. 2025 Oh, that’s right, there’s a measles vaccines that is over 97% efficacious against the measles after two doses are administered, which people have been getting for years. Bruce Y. Lee, Forbes, 15 Mar. 2025 See All Example Sentences for efficacious
Recent Examples of Synonyms for efficacious
Adjective
  • An efficient storage system is a cost-effective storage system.
    Eric Herzog, Forbes.com, 17 June 2025
  • The time cap helped J.J. stay focused and efficient.
    Nasha Smith, People.com, 16 June 2025
Adjective
  • Second, sugarcane is more effective at sequestering carbon than corn.
    SJ Studio, Sourcing Journal, 16 June 2025
  • Flummoxed in Congress, organizing back home The pushback to Trump has been slow in starting as congressional Democrats, outnumbered in both chambers, continue to struggle to devise the strongest message and most effective tactics to use against the Republican president.
    Susan Page, USA Today, 16 June 2025
Adjective
  • The oil-free version of its Vogue Verified counterpart, this one provides powerful antioxidant protection while limiting oil production and reducing breakouts through a potent blend of l-ascorbic acid, silymarin, ferulic acid, and salicylic acid.
    Jenny Berg, Vogue, 13 June 2025
  • This week, Drake teams up with Canadian rap newcomer Smiley, Kim Gordon has a potent pro-freedom message for Donald Trump, and Colombian hitmaker Feid surprise releases his seventh studio album.
    Rolling Stone, Rolling Stone, 13 June 2025

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Cite this Entry

“Efficacious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficacious. Accessed 26 Jun. 2025.

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