ef·​fi·​ca·​cious | \ ˌe-fə-ˈkā-shəs How to pronounce efficacious (audio) \

Definition of efficacious

: having the power to produce a desired effect an efficacious remedy

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Other Words from efficacious

efficaciously adverb
efficaciousness noun

Choose the Right Synonym for efficacious

effective, effectual, efficient, efficacious mean producing or capable of producing a result. effective stresses the actual production of or the power to produce an effect. an effective rebuttal effectual suggests the accomplishment of a desired result especially as viewed after the fact. the measures to stop the pilfering proved effectual 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 efficacious suggests possession of a special quality or virtue that gives effective power. a detergent that is efficacious in removing grease

Examples of efficacious in a Sentence

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

Recent Examples on the Web

The associated novel regimen will hopefully provide a shorter, more easily manageable and highly efficacious treatment for those in need. Beth Mole, Ars Technica, "How a new antibiotic destroys extremely drug-resistant tuberculosis," 16 Aug. 2019 In the past 20 years, this technology has proved efficacious. Costas Synolakis, WSJ, "The Art of Predicting Unpredictable Tsunamis," 3 Oct. 2018 Skinfix has quite literally built its name on offering efficacious products that address a variety of skin concerns, including dryness and eczema. Karina Hoshikawa, Allure, "Exclusive: Skinfix's Products Are Getting More Eco-Friendly Packaging — and Coming to Sephora," 19 Mar. 2019 The brand's Vitamin C Serum and D-Bronzi Serum are everything, and people swear by the line's efficacious yet gentle formulas. Bella Cacciatore, Glamour, "Drunk Elephant's Vegan Retinol Doesn't Irritate My Sensitive Skin," 26 Dec. 2018 Fast forward to today, where advancements have made the aluminum salts in antiperspirants efficacious but mild, says Melissa Torres, manager for North America deodorants and antiperspirants at Degree. Cassie Shortsleeve, Popular Mechanics, "How 5 Everyday Products Have Changed Through the Ages," 10 Dec. 2018 Sometimes expletives are just entertaining and efficacious, and this is particularly true for people in positions of power—which, by its very nature, has a way of conferring the Bad Mouthkeeping Seal of Approval on anything a person chooses to say. Gully Wells, Town & Country, "Elegant Expletives: A Socialite's Guide to the F-Bomb," 7 Aug. 2014 What makes this product so efficacious is its combination of hydrating ingredients, which are extra strong because they're designed for the feet. Rachel Jacoby Zoldan, SELF, "This Foot Cream Is Actually the Best Hand Cream of All Time," 12 Oct. 2018 Sephora: The cosmetics mecca is offering a sweet deal on their affordably priced but super efficacious in-house line, Sephora Collection. Rachel Jacoby Zoldan, Glamour, "The Best Memorial Day 2018 Beauty Sales to Shop This Weekend," 23 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'efficacious.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of efficacious

1528, in the meaning defined above

History and Etymology for efficacious

borrowed from Middle French efficace "effective" or its source Latin efficāc-, efficāx "capable of fulfilling a function, effective" (from efficere "to make, bring about, produce, carry out" + -āc-, -āx, deverbal suffix denoting habitual or successful performance) + -ious — more at effect entry 1, audacious

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Last Updated

26 Aug 2019

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Time Traveler for efficacious

The first known use of efficacious was in 1528

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More Definitions for efficacious



English Language Learners Definition of efficacious

formal : having the power to produce a desired result or effect

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More from Merriam-Webster on efficacious

Rhyming Dictionary: Words that rhyme with efficacious

Thesaurus: All synonyms and antonyms for efficacious

Spanish Central: Translation of efficacious

Nglish: Translation of efficacious for Spanish Speakers

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