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

These are just some of the many harmful chemicals and toxins that are present in vape products. —Omer Awan, Forbes.com, 1 Sep. 2025

According to the Vermont Department of Health, cyanobacteria, or blue-green algae that grow in freshwater, can release toxins into the water that create unsafe swimming conditions. —Thao Nguyen, USA Today, 1 Sep. 2025

Though the effects on fruit flies don’t perfectly mirror effects on humans, the flies show what systems in humans are likely affected by the same toxins. —Austin Corona, AZCentral.com, 30 Aug. 2025

Rising temperatures increase the frequency of harmful algal blooms, which can produce toxins that affect wildlife and human health. —Chicago Tribune, 30 Aug. 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