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[tok-sin] /ˈtɒk sɪn/
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.
Origin of toxin
First recorded in 1885-90; tox(ic) + -in2
Can be confused
toxic, toxin. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for toxin
Contemporary Examples
Historical Examples
  • The determining test for a toxin is its action on a living cell.

    The Fundamentals of Bacteriology Charles Bradfield Morrey
  • Probably it was the toxin in the blood which poisoned the heart.

    Aaron's Rod D. H. Lawrence
  • Now I have said enough about the toxin and some little about the anti-toxin of the Mind.

    Nuggets of the New Thought

    William Walker Atkinson,
  • "This bottle contains a weak solution of the toxin of fatigue," persisted Kennedy.

    The Social Gangster Arthur B. Reeve
  • When this vital seat is poisoned by the toxin, death is instantaneous.

    More Hunting Wasps J. Henri Fabre
British Dictionary definitions for toxin


any of various poisonous substances produced by microorganisms that stimulate the production of neutralizing substances (antitoxins) in the body See also endotoxin, exotoxin
any other poisonous substance of plant or animal origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for toxin

"organic poison," especially one produced by bacteria in an animal body, 1886, from toxic + -in (2).

Online Etymology Dictionary, © 2010 Douglas Harper
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toxin in Medicine

toxin tox·in (tŏk'sĭn)
A poisonous substance, especially a protein, that is produced by living cells or organisms and is capable of causing disease when introduced into the body tissues but is often also capable of inducing neutralizing antibodies or antitoxins.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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toxin in Science
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. Compare antitoxin.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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