# toxin

/ˈtɑksən/ (US) · /tˈɒksɪn/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/toxin
Updated: 2026-05-06

## Definition

a poisonous substance produced by a living thing, like a plant or an animal. It can make people or other creatures sick.

For teachers: a poisonous substance produced within living cells or organisms. Often distinguished from synthetic poisons by its biological origin.

## Examples

- The snake uses a powerful toxin to paralyze its prey.
- Scientists are studying how the toxin from certain mushrooms affects the human nervous system.
- While some bacteria are harmless, others release a potent toxin into the bloodstream that can lead to severe systemic inflammation if not treated immediately.

## Usage notes

- Often used in the plural when referring to different types of poisonous substances.

---

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.