Toxin

n. something poisonous

For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. A toxin (Greek: , toxikon, lit. (poison) for use on arrows) is a poisonous substance produced by living cells or organisms. Toxins are nearly always proteins that are capable of causing disease on contact or absorption with body tissues by interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin).
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Toxin /tox·in/ a poison, especially a protein or conjugated protein produced by some higher plants, certain animals, and pathogenic bacteria, that [more]Toxin - Community and Resources

Noun
1. a poisonous substance produced during the metabolism and growth of certain microorganisms and some higher plant and animal species
(hypernym) poison, poisonous substance
(hyponym) ricin, ricin toxin

n. toxin, something poisonous