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 formstox·i·cal·ly, adverbhy·per·tox·ic, adjectivenon·tox·ic, adjectivenon·tox·i·cal·ly, adverbpost·tox·ic, adjectiveun·tox·ic, adjectiveun·tox·i·cal·ly, adverb
Can be confusedtoxic toxin Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for toxic

Contemporary Examples of toxic

Historical Examples of toxic

  • 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.

  • 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 Formstoxically, adverb

Word Origin for toxic

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

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

toxic in Medicine




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

toxic in Science



Relating to or caused by a toxin.
Capable of causing injury or death, especially by chemical means; poisonous.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.