adverse

UK: /ˈædvɜː^rs/ US: /ædˈvɝs, ˈædvɝs/ ,(ad vûrs′, ad′vûrs)

WordReference Random House Learner's Dictionary of American English © 2025

ad•verse /ædˈvɜrs, ˈædvɜrs/   adj. [before a noun]

1. unfavorable or antagonistic:
   adverse criticism.
2. opposing one's interests or wishes:
   adverse circumstances.
3. being in an opposite direction:
   adverse winds.

ad•verse•ly, adv. 
ad•verse•ness, n. [uncountable] See -vert-.

WordReference Random House Unabridged Dictionary of American English © 2025

ad•verse  (ad vûrs′, ad′vûrs), adj. 

1. unfavorable or antagonistic in purpose or effect:
   adverse criticism.
2. opposing one's interests or desire:
   adverse circumstances.
3. being or acting in a contrary direction;
   opposed or opposing:
   adverse winds.
4. opposite;
   confronting:
   the adverse page.

• Latin adversus hostile (past participle of advertere), equivalent. to ad- ad- + vert- turn + -tus past participle suffix, with -tt- -s-
• Anglo-French, Old French advers
• Middle English 1350–1400

ad•verse′ly, adv. 
ad•verse′ness, n. 
Synonyms

• 1. hostile, inimical, unfriendly.
• 2. unfavorable; unlucky, unfortunate; disastrous, calamitous, catastrophic. See contrary. 

Antonyms

• 1. –3. favorable.

Usage

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.

Collins Concise English Dictionary © HarperCollins Publishers::

adverse / 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

Etymology: 14th Century: from Latin adversus opposed to, hostile, from advertere to turn towards, from ad- to, towards + vertere to turn

adˈversely adverb

adˈverseness noun