# adverse

/ˈædˌvɝs/ (US) · /ædvˈɜːs/ (UK)

Source: https://englishreference.com/word/adverse
Updated: 2026-06-20

## Senses

### 1. harmful or unfavourable

adjective · CEFR C1 · Formal · Academic

harmful, negative, or preventing success.

For teachers: unfavourable or antagonistic in effect; acting against one's interests or welfare.

- The match was cancelled due to adverse weather conditions.
- The pharmaceutical company was forced to halt the clinical trial after several participants reported adverse reactions to the new medication.

Usage: Commonly collocates with 'weather', 'conditions', 'effects', and 'reactions'.

Teaching tip: Learners frequently confuse this with 'averse'. Remind them that 'adverse' usually describes things or situations, while 'averse' describes a person's feelings (e.g., 'risk-averse').

### 2. opposite or confronting

adjective · CEFR C2 · Technical · Formal

facing the opposite way or being on the opposite side.

For teachers: positioned in an opposite direction or confronting; often used in technical or botanical contexts.

- The leaves grow in an adverse position along the stem.
- The researcher noted the adverse placement of the sensors, which resulted in conflicting data streams during the initial phase of the experiment.

## Examples

- The medicine had some adverse side effects.
- The outdoor concert was cancelled due to adverse weather conditions that made the stage unsafe.
- Despite the adverse economic climate and rising interest rates, the small startup managed to secure enough venture capital to expand its operations into three new territories.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.