toxin

American  

[tok-sin] / ˈtɒk sɪn /

noun

1. any poison produced by an organism, characterized by antigenicity in certain animals and high molecular weight, and including the bacterial toxins that are the causative agents of tetanus, diphtheria, etc., and such plant and animal toxins as ricin and snake venom.

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toxin British  

/ ˈtɒksɪn /

noun

1. any of various poisonous substances produced by microorganisms that stimulate the production of neutralizing substances (antitoxins) in the body See also endotoxin exotoxin

2. any other poisonous substance of plant or animal origin

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toxin Scientific  

/ tŏk′sĭn /

1. A poisonous substance, especially one produced by a living organism. Toxins can be products or byproducts of ordinary metabolism, such as lactic acid, and they must be broken down or excreted before building up to dangerous levels. Toxins can facilitate survival, as with snake venom that kills or immobilizes prey, or cyanide produced by some plants as a defense against being eaten. Bacterial toxins can sometimes be neutralized with antitoxins.

2. Compare antitoxin

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Related Words

See poison.

Etymology

Origin of toxin

First recorded in 1885–90; tox(ic) + -in ²

Explanation

A toxin is an organic poison — it’s made by plants and animals. Toxins make people sick. If your appendix bursts, toxins are released into your blood stream. Also breathing in a toxin like ricin will make you very ill. Toxins are naturally occurring poisons. There are the toxins your body creates and some that animals and plants excrete. Some are harmful — getting stung by a stingray can kill you because its toxin is powerful. Toxin is the noun form of toxic. The most dangerous kind of toxin is the botulinus toxin, which is the kind found in the bacteria of spoiled food and is used to make Botox. Another dangerous toxin, ricin, is made from castor beans.

Example Sentences

And then, of course, spiders are venomous, toting enough toxin to immobilize and liquify prey and, in a few cases, cause lesions, necrosis or death in humans.

From The Wall Street Journal • May 15, 2026

Ingesting too much of the toxin may also cause cancers of the kidney and prostate, it says.

From Barron's • May 13, 2026

A March bill sponsored by Lara would establish toxin limits and mandate testing before and after cleanups.

From Los Angeles Times • May 1, 2026

Botulinum toxin - commonly known by the brand name Botox - is more widely known for its use as a cosmetic treatment which works by blocking signals from the nerves that control the facial muscles.

From BBC • Mar. 19, 2026

The toxin should have dissipated, but I don’t want to put any of us through that right now.

From "The Last Cuentista" by Donna Barba Higuera

Related Words

• contamination
• germ
• infection
• venom
• virus