adverse

adjective

ad·​verse ad-ˈvərs 

ˈad-ˌvərs

1

: acting against or in a contrary direction : hostile

hindered by adverse winds

2

a

: 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

adverseness noun

Did you know?

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.

Synonyms of adverse

• unfavorable
• negative
• hostile

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

Recent Examples on the Web

Poor Bella’s horribly adverse reaction to the virus makes for a great jump scare in the moment and also an exclamation point on the season overall, emphasizing that no one really understands how this virus works. —Roxana Hadadi, Vulture, 10 Mar. 2026

The company said the letter largely sought more details about the steps the company has taken since the inspection to comply with post-marketing adverse drug experience, or PADE, regulations. —Emily Mae Czachor, CBS News, 10 Mar. 2026

Earlier monitoring allows for early treatments should adverse changes occur. —Md Published, Verywell Health, 10 Mar. 2026

Ollongren also warned of the deteriorating security situation in the Middle East and the war’s adverse effects on human rights in Iran and the broader region. —Morgan Chalfant, semafor.com, 9 Mar. 2026

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing adverse

• adverse effects

Rhymes for adverse

• averse
• coerce
• disburse
• disperse
• diverse
• immerse
• inverse
• obverse
• perverse
• rehearse
• reverse
• transverse

Kids Definition

adverse

adjective

ad·​verse ad-ˈvərs 

ˈad-ˌvərs

1

: acting in an opposite direction

adverse winds

2

: opposed to one's interests

adverse testimony

especially : not friendly or favorable

adverse criticism

3

: causing harm

adverse effects of a drug

adversely adverb

adverseness noun

Legal Definition

adverse

adjective

ad·​verse ad-ˈvərs, ˈad-ˌvərs 

: opposed to one's interests : operating to one's detriment

an adverse verdict