toxin

noun

tox·​in ˈtäk-sən 

: a poisonous substance that is a specific product of the metabolic activities of a living organism and is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation

Did you know?

Toxins Are Often Found in Nature

Long before chemists started creating poisons from scratch, humans were employing natural toxins for killing weeds and insects. For centuries South American tribes have used the toxin curare, extracted from a native vine, to tip their arrows. The garden flower called wolfsbane or monkshood is the source of aconite, an extremely potent toxin. The common flower known as jimsonweed contains the deadly poison scopolamine. And the castor-oil plant yields the almost unbelievably poisonous toxin called ricin. Today we hear health advisers of all kinds talk about ridding the body of toxins; but they're usually pretty vague about which ones they mean, and most of these "toxins" wouldn't be called that by biologists.

Synonyms

• poison
• toxic
• disease
• venom

Examples of toxin in a Sentence

the toxin in scorpion venom

read a pamphlet on the toxin responsible for botulism, a food poisoning that can cause paralysis and even death in some cases

Recent Examples on the Web

This bacterial strain, often found on your skin, produces toxins that can cause food poisoning in people who consume contaminated food. —Sarah Bradley, Health, 10 July 2025

Members receive comprehensive diagnostic testing each year, including biomarker panels and specialty tests that evaluate hormones, genetics and potential toxin exposure. —Lauryn Higgins, Flow Space, 10 July 2025

That smoke can also include toxins, such as lead when cars and homes burn. —ArsTechnica, 9 July 2025

By studying the samples, the biologists could look at algal toxin concentrations in the food web, Lefebvre. —Julia Jacobo, ABC News, 9 July 2025

Word History

Etymology

International Scientific Vocabulary

First Known Use

1887, in the meaning defined above

Phrases Containing toxin

• botulinum toxin
• environmental toxin

Rhymes for toxin

• coxon
• oxen
• tocsin
• aflatoxin
• antitoxin
• digitoxin
• endotoxin
• exotoxin
• ferredoxin
• mycotoxin
• neurotoxin
• picrotoxin

Kids Definition

toxin

noun

tox·​in ˈtäk-sən 

: a substance produced by a living organism (as a bacterium) that is very poisonous to other organisms and that usually causes antibody formation compare antitoxin

Etymology

derived from Latin tox- "poisonous" and English -in "chemical compound"; tox- from toxicum "poison," from Greek toxikon "arrow poison," from toxon "bow, arrow" — related to intoxicate, toxic see Word History at intoxicate

Medical Definition

toxin

noun

tox·​in ˈtäk-sən 

: a colloidal proteinaceous poisonous substance that is a specific product of the metabolic activities of a living organism and is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation