ad·​verse | \ad-ˈvərs, ˈad-ˌ\

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

adversely adverb
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

Moreover, depression is a risk factor for adverse outcomes in cardiovascular disease patients. Nicholas Bakalar, New York Times, "Midlife Fitness May Protect Against Later Depression," 27 June 2018 Jean is right, there are correlations between screen time and adverse mental-health outcomes. Jeanne Whalen, WSJ, "Is Screen Time Bad for Children’s Mental Health?," 24 June 2018 That's contributed to a 1.42 WHIP, which creates too many adverse situations for a group that's still trying to find its footing without closer Zach Britton. Jon Meoli,, "Five Orioles stats that stand out: Fun with small sample sizes through season's first two weeks," 12 Apr. 2018 The organization is especially troubled about the potential health effects on students who attend schools along the freeway, because children are more vulnerable to the adverse health effects of air pollution. Alex Park, Houston Chronicle, "Air pollution poses health risk to Houstonians, study finds," 3 July 2018 Kaminski’s own research investigates ways to reduce soccer’s adverse effects on the brain. Daniel Ackerman, Scientific American, "Avoiding the “Bobblehead Effect”: Strength Training Could Help Soccer Players," 29 June 2018 The study examined drugs that list possible adverse side effects including depression and suicide, but that does not mean the link was always well-characterized — or that people should stop taking a drug that could be helping them. Carolyn Y. Johnson, Anchorage Daily News, "More than a third of American adults take prescription drugs that may increase risk of depression, study says," 13 June 2018 Importantly, Mendell said the patients treated so far are showing no signs of adverse immune reactions, no kidney issues, and no drops in red blood cells or platelet counts. Adam Feuerstein, STAT, "With tantalizing early results, Sarepta’s gene therapy for Duchenne raises hopes for ‘real change’," 19 June 2018 His son thinks his father had an adverse reaction to a combination of medicines, and perhaps lost consciousness before crashing into the river. Katy Moeller, idahostatesman, "Family of missing Boise man says sheriff notified them of human bone found in river," 6 June 2018

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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Statistics for adverse

Last Updated

6 Nov 2018

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Time Traveler for adverse

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

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More Definitions for adverse



English Language Learners Definition of adverse

: bad or unfavorable : not good


ad·​verse | \ad-ˈvərs \

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 \

Legal Definition of adverse 

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

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Comments on adverse

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