# poisonous

/ˈpɔɪzənəs/ (US) · /pˈɔɪzənəs/ (UK)

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

## Senses

### 1. dangerous to eat or touch

adjective · CEFR B1

describes something that contains a substance that can cause illness or death if it enters your body.

For teachers: containing or producing a substance that causes injury, illness, or death when absorbed or ingested.

- Be careful not to eat those berries because they are poisonous.
- The bright colours of certain tropical frogs serve as a warning to predators that their skin is highly poisonous.

Usage: Often used with 'to' to indicate who is at risk, such as 'poisonous to humans'.

### 2. harmful or unpleasant

adjective · CEFR B2

describes a person, feeling, or situation that is very negative and harmful to others.

For teachers: extremely unpleasant, malicious, or harmful in a figurative sense; often applied to social atmospheres or interpersonal relationships.

- He decided to leave the company because of the poisonous atmosphere in the office.
- The politician's poisonous rhetoric served only to further divide the community during the election cycle.

Teaching tip: This figurative sense is very common in modern workplace and relationship discussions, often interchangeable with 'toxic'.

## Examples

- Be careful because those bright red berries are poisonous.
- The hikers were warned to stay away from the poisonous mushrooms growing near the base of the trees.
- While some snakes use venom to hunt, many amphibians rely on poisonous skin secretions to deter potential predators from attacking them.

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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.