Synonyms of efficacious

efficacious

adjective

ˌe-fə-ˈkā-shəs 

as in efficient

producing or capable of producing a desired result

taking a cookie break while studying is one of the most efficacious ways of rejuvenating the mind that I have ever discovered

Synonyms & Similar Words

• efficient
• effective
• potent
• productive
• effectual
• adequate
• fruitful
• operative
• useful
• capable
• practical
• convincing
• practiced
• adept
• skilled
• proficient
• practised
• competent
• expert
• feasible
• skillful
• experienced
• practicable
• cogent
• useable
• valid
• accomplished
• realizable
• dynamic
• masterly
• active
• striking
• hyperefficient
• veteran
• workable
• telling
• ultraefficient
• killer
• functional
• usable
• applicable
• sound
• consummate
• versed
• virtuoso
• working

Antonyms & Near Antonyms

• ineffective
• useless
• inefficient
• ineffectual
• fruitless
• inoperative
• incapable
• unproductive
• counterproductive
• incompetent
• unskilled
• inexperienced
• futile
• vain
• unqualified
• unfruitful
• unsuccessful
• abortive
• empty
• hollow
• idle
• unprofitable
• worthless
• pointless
• unskillful
• inexpert
• inoperative
• unseasoned
• unavailing
• bootless

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

Recent Examples of efficacious

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

On the other side are patients living with untreated diseases hoping that pharmaceutical companies will soon develop an efficacious treatment. —Wayne Winegarden, Forbes, 5 Mar. 2025

This intimate approach delivers highly bespoke and efficacious treatments. —Bea McMonagle, Forbes, 28 Feb. 2025

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