ad·​verse | \ ad-ˈvərs How to pronounce adverse (audio) , ˈad-ˌvərs \

Definition of adverse

1 : acting against or in a contrary direction : hostile hindered by adverse winds
2a : opposed to one's interests an adverse verdict heard testimony adverse to their position especially : unfavorable adverse criticism
b : causing harm : harmful adverse drug effects
3 archaic : opposite in position

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Other Words from adverse

adverseness noun

Adverse vs. Averse

Many people find themselves confused when faced with the choice between adverse and averse. While these two adjectives have many similarities, they are not used interchangeably.

If you want to describe a negative reaction to something (such as a harmful side effect from medication) or dangerous meteorological conditions (such as a snowstorm), adverse is the correct choice; you would not say that you had an averse reaction to medication or that there was averse weather.

Averse is most commonly followed by the preposition to (as in "she is averse to shellfish"), but not in every case; you can, for example, describe someone as “risk averse." Normally, averse to signifies a degree of dislike and avoidance, but when preceded by the word not (as in “he was not averse to having another drink”), it may be used as a pointedly understated way to express an interest in something.

In short, adverse tends to be used to describe effects, conditions, and results; while averse refers to feelings and inclinations.

Examples of adverse in a Sentence

The Bankruptcy Code requires that debtor's counsel be disinterested and not have an interest adverse to the estate. Lawyers Weekly USA, 4 Oct. 1999 On more than one occasion his decrees provoked riots, and there were those who voiced adverse opinions on the Duke in public. — Alison Weir, The Princes in the Tower, 1992 The plant tolerates adverse conditions … — Dave Dunn, Fine Gardening, January/February 1991 all the adverse publicity really caused the movie star's popularity to suffer the adverse effects of the drug are too severe to allow it to be marketed
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Recent Examples on the Web Experts recommend that the drugs be tested in infected animals to make sure that there are no adverse side effects. Dallas News, "UT Southwestern scientists investigate pneumonia drug as possible COVID-19 treatment," 1 July 2020 Adverse life events, as Fisher puts it, expose people unevenly to adverse health events. Laura Stark, The New Republic, "The Hidden Racism of Vaccine Testing," 29 June 2020 But the new trial shows that the drug had no effect on mild cases of coronavirus — including no clear adverse effects — and could be a game-changer in dire situations. Molly Longman,, "What Is Dexamethasone & Will It Help Coronavirus Patients?," 29 June 2020 Research shows airborne dust can have adverse effects on health, with one of the most important being pulmonary disease. Jeff Berardelli, CBS News, "Massive Sahara desert dust plume closing in on the United States," 26 June 2020 The intended targets aren’t the only ones who suffer the adverse effects of DDoSes. Dan Goodin, Ars Technica, "Two record DDoSes disclosed this week underscore their growing menace," 25 June 2020 The lawsuit, filed in D.C. Superior Court, alleges that the companies have known about the adverse environmental effects of their products since the 1950s. Emily Davies, Washington Post, "D.C. attorney general sues oil and gas companies, alleging industry misled public about climate change," 25 June 2020 Too much zinc in supplement form can trigger adverse effects that include nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches. Cynthia Sass, Rd,, "Zinc Supplements: What to Know if You're Thinking of Taking Them," 24 June 2020 In practical terms, the longer the border stays closed to nonessential travel, the more likely that closure is to reduce cross-border travel for some time and have lasting adverse effects on U.S. border economies. Jeremy Lott, Washington Examiner, "Border towns adversely hit as US and Canada extend nonessential travel ban," 18 June 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'adverse.' 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 adverse

14th century, in the meaning defined at sense 1

History and Etymology for adverse

Middle English, borrowed from Anglo-French advers, borrowed from Latin adversus "turned toward, facing, opposed," from past participle of advertere "to turn toward, direct" — more at advert entry 1

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Time Traveler for adverse

Time Traveler

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

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Statistics for adverse

Last Updated

6 Jul 2020

Cite this Entry

“Adverse.” Dictionary, Merriam-Webster, Accessed 13 Jul. 2020.

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More Definitions for adverse


How to pronounce adverse (audio)

English Language Learners Definition of adverse

: bad or unfavorable : not good


ad·​verse | \ ad-ˈvərs How to pronounce adverse (audio) \

Kids Definition of adverse

1 : acting against or in an opposite direction adverse winds
2 : not helping or favoring adverse circumstances

Other Words from adverse

adversely adverb Bad weather adversely affected attendance at the fair.


ad·​verse | \ ad-ˈvərs, ˈad-ˌvərs How to pronounce adverse (audio) \

Legal Definition of adverse

: opposed to one's interests : operating to one's detriment an adverse verdict

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More from Merriam-Webster on adverse

Thesaurus: All synonyms and antonyms for adverse

Rhyming Dictionary: Words that rhyme with adverse

Spanish Central: Translation of adverse

Nglish: Translation of adverse for Spanish Speakers

Britannica English: Translation of adverse for Arabic Speakers

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