ef·​fec·​tive | \ i-ˈfek-tiv How to pronounce effective (audio) , e-, ē-, ə- \

Definition of effective

 (Entry 1 of 2)

1a : producing a decided, decisive, or desired effect an effective policy
b : impressive, striking a gold lamé fabric studded with effective … precious stones— Stanley Marcus
2 : being in effect : operative the tax becomes effective next year
3 : actual the need to increase effective demand for goods
4 : ready for service or action effective manpower
5 of a rate of interest : equal to the rate of simple interest that yields the same amount when the interest is paid once at the end of the interest period as a quoted rate of interest does when calculated at compound interest over the same period — compare nominal sense 4



Definition of effective (Entry 2 of 2)

: one that is effective (see effective entry 1) especially : a soldier equipped for duty

Other Words from effective


effectiveness noun
effectivity \ ˌe-​ˌfek-​ˈti-​və-​tē How to pronounce effective (audio) , i-​ , ē-​ , ə-​ \ noun

Choose the Right Synonym for effective


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

Comparing Efficient, Effective, and Proficient


These three words cover some overlapping territory.

Efficient most often describes what is capable of producing desired results without wasting materials, time, or energy. While the word can be applied to both people and things, it is far more commonly applied to things, such as machines, systems, processes, and organizations. The focus of the word is on how little is wasted or lost while the desired results are produced.

Effective typically describes things—such as policies, treatments, arguments, and techniques—that do what they are intended to do. People can also be described as effective when they accomplish what they set out to accomplish, but the word is far more often applied to things.

Proficient typically describes people, and it often is followed by the preposition at. If you are proficient at something, you are very good at it. You are, in fact, so good at doing it that you are unusually efficient when you do it. One can also be proficient in something, such as a language.

Examples of effective in a Sentence

Adjective These commercials were extremely effective as marketing tools, but we now know that chocolate swimming pools and candy-coating showers play no part in the manufacture of real M&M's. Instead, the ellipsoid chocolate centers of plain M&M's are formed by machines. — David Owen, Atlantic, October 1988 My feeling is that by waiting for the right moment to let rip, a film is infinitely more effective, especially with characters you have come to like. — Clive Barker, in Cinefantastique, September 1987 But Tammy's most effective remedy for stress, both then and now, was the same as Imelda Marcos's: shopping up a storm. "It's kind of a hobby to help my nerves," she explained … — Jean Seligman, Newsweek, 8 June 1987 It's a simple but effective technique. He gave an effective speech.
Recent Examples on the Web: Adjective Instead, America got McConnell, a superb political strategist and tactician who was extraordinarily effective in achieving his partisan objectives, at great cost to the Senate and the country that depended on it. Ira Shapiro, The New Republic, 6 May 2022 In a country where more than half of registered voters are 40 or younger, TikTok has been particularly effective in efforts to whitewash the history of the Marcos family. Los Angeles Times, 5 May 2022 Instead of antibiotics, Blanton counsels people who want to be proactive to try taking daily Pepto-Bismol, which contains bismuth subsalicylate and can be up to 65 percent effective in preventing traveler’s diarrhea. Washington Post, 5 May 2022 Often, organizations administer behavioral assessments to support employees in developing self-awareness, and research indicates that this tool is very effective in creating psychological safety in the workplace. Reena Khullar Sharma, Forbes, 2 May 2022 Chris Ballard and the Colts were effective in addressing needs without a first-rounder. Scott Horner, The Indianapolis Star, 1 May 2022 Last June, Novavax said the vaccine was 90% effective in preventing people from falling ill in a 30,000-person trial conducted when variants had begun to complicate the pandemic in the United States and Mexico. Laurie Mcginley, Carolyn Y. Johnson, Anchorage Daily News, 29 Apr. 2022 China’s Covid-19 control measures, which combine frequent testing with restrictions on movement, have been effective in lowering the number of new cases in much of the country, including Shanghai, health authorities said Thursday. Wenxin Fan, WSJ, 28 Apr. 2022 The couples in which at least one partner reported experiencing flooding were the same ones whom the researchers judged to be less effective in finding solutions to their conflict. Arthur C. Brooks, The Atlantic, 28 Apr. 2022 Recent Examples on the Web: Noun Laurent Morali, president of Kushner Cos., will take over as chief executive effective immediately, the firm said. Peter Grant, WSJ, 19 Oct. 2021 California’s coronavirus dashboard showed an R-effective of 0.81 for San Francisco as of Wednesday. Kellie Hwang, San Francisco Chronicle, 9 June 2021 AstraZeneca is working with the Serum Institute, as is Novavax, whose vaccine looks to be ninety-six-per-cent effective. Sue Halpern, The New Yorker, 3 June 2021 One way is through applied topical insect repellent, the most (and arguably only) effective of which contain DEET. Larry Olmsted, Forbes, 28 Apr. 2021 But even for a team loaded at the position, the effective of Oregon’s ground game, especially in the second half, in its first two games is outlandish. oregonlive, 18 Nov. 2020 The agency had already announced that a vaccine would have to prove at least 50-percent effective at preventing COVID-19 to earn full approval. Beth Mole, Ars Technica, 24 Sep. 2020 In this scenario, infections will decline even if face masks are only 50-percent effective. John Timmer, Ars Technica, 12 June 2020 See More

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

First Known Use of effective


14th century, in the meaning defined at sense 1a


1708, in the meaning defined above

History and Etymology for effective


Middle English effectif, borrowed from Late Latin effectīvus "producing a result, efficient," going back to Latin, "involving an end product," from effectus, past participle of efficere "to make, bring about, produce, carry out" + -īvus -ive — more at effect entry 1


derivative of effective entry 1

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The first known use of effective was in the 14th century

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Last Updated

10 May 2022

Cite this Entry

“Effective.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/effective. Accessed 19 May. 2022.

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More Definitions for effective


ef·​fec·​tive | \ i-ˈfek-tiv How to pronounce effective (audio) \

Kids Definition of effective

1 : producing or able to produce a desired effect an effective vaccine
2 : impressive an effective speech
3 : being in operation The rule is effective immediately.

Other Words from effective

effectively adverb
effectiveness noun


ef·​fec·​tive | \ i-ˈfek-tiv How to pronounce effective (audio) \

Medical Definition of effective

: producing a decided, decisive, claimed, or desired effect a drug judged effective by an evaluating panel

Other Words from effective

effectively adverb
effectiveness noun



Legal Definition of effective

1 : producing a desired effect an effective revocation of the contract
2 : capable of bringing about an effect effective assistance of counsel — see also ineffective assistance of counsel
3 : being in effect
4 of a rate of interest : equal to the rate of simple interest that yields the same amount when the rate is paid once at the end of the interest period as a quoted rate of interest does when calculated at compound interest over the same period — compare nominal

Other Words from effective

effectiveness noun

More from Merriam-Webster on effective

Nglish: Translation of effective for Spanish Speakers

Britannica English: Translation of effective for Arabic Speakers


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