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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Synonym Usage

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

As a result, individuals living near agricultural zones may still encounter the toxin through dust and outdoor air.

From Science Daily • May 21, 2026

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

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

From Los Angeles Times • May 1, 2026

It rose for every category except infant formula, where Nestlé recalled some products in January due to concerns they contained a toxin that can cause food poisoning.

From Barron's • Apr. 23, 2026

The toxin does the deed insidiously, indirectly, by inhibiting an enzyme essential to glycoprotein metabolism.

From "Into the Wild" by Jon Krakauer

Related Words

• contamination
• germ
• infection
• venom
• virus