adverse

American  

[ad-vurs, ad-vurs] / ædˈvɜrs, ˈæd vɜrs /

adjective

1. unfavorable or antagonistic in purpose or effect.

   adverse criticism.

   Synonyms:

   unfriendly, inimical, hostile

   Antonyms:

   favorable

2. opposing one's interests or desire.

   adverse circumstances.

   Synonyms:

   catastrophic, calamitous, disastrous, unfortunate, unlucky, unfavorable

   Antonyms:

   favorable

3. being or acting in a contrary direction; opposed or opposing.

   adverse winds.

   Antonyms:

   favorable

4. opposite; confronting.

   the adverse page.

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adverse British  

/ ˈædvɜːs, ædˈvɜːs /

adjective

1. antagonistic or inimical; hostile

   adverse criticism

2. unfavourable to one's interests

   adverse circumstances

3. contrary or opposite in direction or position

   adverse winds

4. (of leaves, flowers, etc) facing the main stem Compare averse

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Usage

What's the difference between adverse and averse? Adverse most commonly means unfavorable or hostile, as in adverse conditions, adverse weather, or adverse criticism. Averse means strongly opposed to or having a feeling of strong dislike toward something, as in I’m extremely averse to taking on debt. Averse is often used in negative constructions, as in We are not averse to negotiations. It’s also used in the term risk-averse, meaning reluctant to take risks or tending to avoid risk. Confusion can arise between the two terms because both are adjectives that involve unfavorableness or opposition. However, adverse typically describes circumstances, while averse typically describes the way someone feels toward something. One way to remember which word is which is to remember that adverse, in a very general sense, means bad, which rhymes with the first part of the word. On the other hand, when you’re averse to something, you have a very strong opposition to it. It may also be helpful to remember that the noun form of adverse is adversity, which means hostile or unfavorable conditions. The noun form of averse is aversion, meaning a strong feeling of dislike or opposition. Here’s an example of adverse and averse used correctly in a sentence. Example: I’m not averse to taking risks for the sake of adventure, but I just don’t think it’s safe to skydive in such adverse weather. Want to learn more? Read the full breakdown of the difference between adverse and averse.

Commonly Confused

The adjectives adverse and averse are related both etymologically and semantically, each having “opposition” as a central sense. Adverse is seldom used of people but rather of effects or events, and it usually conveys a sense of hostility or harmfulness: adverse reviews; adverse winds; adverse trends in the economy. Related nouns are adversity and adversary: Adversities breed bitterness. His adversaries countered his every move. Averse is used of persons and means “feeling opposed or disinclined”; it often occurs idiomatically with a preceding negative to convey the opposite meaning “willing or agreeable,” and is not interchangeable with adverse in these contexts: We are not averse to holding another meeting. The related noun is aversion: She has a strong aversion to violence. Averse is usually followed by to, in older use occasionally by from.

Related Words

See contrary.

Other Word Forms

• adversely
  adverb
• adverseness
  noun
• unadverse
  adjective
• unadverseness
  noun

Etymology

Origin of adverse

First recorded in 1350–1400; Middle English, from Anglo-French, Old French advers, from Latin adversus “hostile” (past participle of advertere ), equivalent to ad- ad- + vert- “turn” + -tus past participle suffix, with -tt- giving rise to -s-

Explanation

Steer clear of anything adverse. If it's adverse, it's working against you — like adverse weather conditions or the adverse effects of eating too much sugar. Coming from the Latin adversus meaning "turned against," adverse is an adjective describing a factor that seems to work against or actively harm something. Think of the related word, adversary, which means "enemy or opponent," so that if something is adverse, it acts as if it were the enemy. If you have an adverse reaction to an antibiotic, your doctor will need to prescribe a new medication.

Example Sentences

Adverse effects depend on the level of lead in the food, the age of the consumer and the frequency of exposure, according to the FDA.

From Los Angeles Times • Apr. 2, 2026

The firm cited a non-public disclosure letter outlining situations in which Kenvue’s ongoing Tylenol litigation may constitute a Material Adverse Effect, or an event where the merger can be canceled.

From Barron's • Nov. 3, 2025

The Department of Health said work was ongoing to improve the Serious Adverse Incident review process across Northern Ireland.

From BBC • Oct. 6, 2024

Adverse events may be less likely to show up in these participants than in the general population, Joniak-Grant added.

From Science Magazine • Jun. 5, 2024

Adverse implies hostility or opposition, and usually characterizes a thing or an action.

From "Woe Is I" by Patricia T. O'Conner

Related Words

• conflicting
• detrimental
• disadvantageous
• inimical
• injurious
• negative
• unfortunate
• unfriendly