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[tok-sik] /ˈtɒk sɪk/
of, pertaining to, affected with, or caused by a toxin or poison:
a toxic condition.
acting as or having the effect of a poison; poisonous:
a toxic drug.
causing unpleasant feelings; harmful or malicious:
a toxic boyfriend; toxic criticism.
pertaining to or noting debt that will probably not be repaid:
toxic mortgages.
pertaining to or noting a financial instrument or other asset that has no value or an unknown value because there is no market for it:
toxic mortgage-backed securities.
a toxic chemical or other substance.
Origin of toxic
1655-65; < Late Latin toxicus poisonous, adj. derivative of Latin toxicum poison < Greek toxikón (orig. short for toxikòn phármakon literally, bow poison, i.e., poison used on arrows), equivalent to tóx(on) bow + -ikon, neuter of -ikos -ic
Related forms
toxically, adverb
hypertoxic, adjective
nontoxic, adjective
nontoxically, adverb
posttoxic, adjective
untoxic, adjective
untoxically, adverb
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 toxic
Contemporary Examples
Historical Examples
  • In hollows, or places where the air is stagnant, it may still be toxic.

    When the Sleepers Woke Arthur Leo Zagat
  • The drug was a deadly one, he said, and the toxic dose was still to be determined.

    Hilda Wade Grant Allen
  • Little is known of its toxic action, but a weak toxin has been got from cultures.

    The Flea Harold Russell
  • In dog 28 the first dose of caffein 50 mg per kilo was toxic.

    The Toxicity of Caffein William Salant
  • This drug is one-seventh as toxic as cocaine but is also weaker in action.

British Dictionary definitions for toxic


of, relating to, or caused by a toxin or poison; poisonous
harmful or deadly
(of a financial asset) likely to cause significant loss to the holder
Derived Forms
toxically, adverb
Word Origin
C17: from medical Latin toxicus, from Latin toxicum poison, from Greek toxikon (pharmakon) (poison) used on arrows, from toxon arrow
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 toxic

1660s, from French toxique, from Late Latin toxicus "poisoned," from Latin toxicum "poison," from Greek toxikon (pharmakon) "(poison) for use on arrows," from toxikon, neuter of toxikos "pertaining to arrows or archery," and thus to a bow, from toxon "bow," probably from a Scythian word that also was borrowed into Latin as taxus "yew."

Online Etymology Dictionary, © 2010 Douglas Harper
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toxic in Medicine

toxic tox·ic (tŏk'sĭk)

  1. Of, relating to, or caused by a toxin or other poison.

  2. Capable of causing injury or death, especially by chemical means; poisonous.

A toxic chemical or other substance.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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toxic in Science
  1. Relating to or caused by a toxin.

  2. Capable of causing injury or death, especially by chemical means; poisonous.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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