toxic

adj. poisonous, noxious, deadly

n. poisonous substance

For other use of the term Toxic, see Toxicity (disambiguation).Toxic! was a British weekly comic book published by Apocalypse Ltd. A total of 31 issues were published from March 28th-October 24th 1991.
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Toxicity is the degree to which something is able to produce illness or damage to an exposed organism. Toxicity can refer to the effect on a whole organism, such as a human or a bacterium or a plant, or to a substructure, such as a cell (cytotoxicity) or an organ (organotoxicity such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or "society at large".
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Adjective
1. of or relating to or caused by a toxin or poison; "suffering from exposure to toxic substances"
(antonym) nontoxic, atoxic
(similar) cyanogenetic, cyanogenic
(see-also) harmful

(a.)
Alt. of Toxical
  

Having to do with poison or something harmful to the body. Toxic substances usually cause unwanted side effects.