- any of various poisonous compounds produced by some microorganisms and causing certain diseases
- any of various similar poisons, related to proteins, formed in certain plants, as ricin, or secreted by certain animals, as snake venom: toxins, when injected into animals or humans, typically initiate the formation of antitoxins
tox(ic) + -in
See toxin in American Heritage Dictionary 4
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.
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