toxic
Americanadjective
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of, pertaining to, affected with, or caused by a toxin or poison.
a toxic condition.
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acting as or having the effect of a poison; poisonous.
a toxic drug.
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causing unpleasant feelings; harmful or malicious: toxic criticism.
a toxic boyfriend who wanted complete control over her;
toxic criticism.
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Finance.
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pertaining to or noting debt that will probably not be repaid.
toxic mortgages.
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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.
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noun
adjective
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of, relating to, or caused by a toxin or poison; poisonous
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harmful or deadly
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(of a financial asset) likely to cause significant loss to the holder
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Relating to or caused by a toxin.
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Capable of causing injury or death, especially by chemical means; poisonous.
Other Word Forms
Etymology
Origin of toxic
First recorded in 1655–65; from Late Latin toxicus “poisonous,” derivative of toxicum “poison,” from Greek toxikón (for toxikòn phármakon literally, “bow poison,” i.e., poison used on arrows), equivalent to tóx(on) “bow” + -ikon, neuter of -ikos adjective suffix; see -ic
Explanation
Danger! Hazardous! Do not eat! These are just some of the warnings you'll see on toxic substances — meaning stuff that's poisonous and even deadly. Cobra bites, wild mystery mushrooms and strong chemicals are all toxic. So are certain people, if they have particularly mean personalities. Toxic is related to the word toxin, which is a kind of poison. It comes from the ancient Greek word toxikon, which means "poison for arrows." Some toxic arrows could come in handy for those toxic personalities...
Vocabulary lists containing toxic
Holes
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"Handle with Care"
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The Cardboard Kingdom
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The "Toxic" singer was arrested in March after police spotted her driving erratically on a freeway in Ventura County, near Los Angeles.
From Barron's • May 4, 2026
The bill, AB 1642, would task the state’s Department of Toxic Substances Control with creating standards by July 1, 2027.
From Los Angeles Times • Jan. 28, 2026
Tessa West, a psychology professor at New York University and author of the book “Jerks at Work: Toxic Coworkers and What to Do About Them,” has some suggestions.
From MarketWatch • Jan. 23, 2026
Toxic air is a recurring problem in Delhi and its suburbs, especially during winters.
From BBC • Dec. 3, 2025
“You have to tell your emotional truth,” says Susan Forward, a therapist and the best-selling author of Toxic Parents.
From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
