toxic

American  

[tok-sik] / ˈtɒk sɪk /

adjective

1. of, pertaining to, affected with, or caused by a toxin or poison.

   a toxic condition.

2. acting as or having the effect of a poison; poisonous.

   a toxic drug.

3. causing unpleasant feelings; harmful or malicious: toxic criticism.

   a toxic boyfriend who wanted complete control over her;

   toxic criticism.

4. Finance.

   1. pertaining to or noting debt that will probably not be repaid.

      toxic mortgages.

   2. 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

• toxics
  plural

1. a toxic chemical or other substance.

toxic British  

/ ˈtɒksɪk /

adjective

1. of, relating to, or caused by a toxin or poison; poisonous

2. harmful or deadly

3. (of a financial asset) likely to cause significant loss to the holder

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toxic Scientific  

/ tŏk′sĭk /

1. Relating to or caused by a toxin.

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

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Other Word Forms

Derived Forms

• hypertoxic
  adjective
• nontoxic
  adjective
• posttoxic
  adjective
• untoxic
  adjective
• nontoxically
  adverb
• toxically
  adverb
• untoxically
  adverb

Inflected Forms

Nouns

• toxics
  plural

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...

Example Sentences

See Examples For:

toxic toxics

Australian toxic mushroom killer Erin Patterson launches an appeal Wednesday against her conviction in a triple-murder case that made headlines worldwide.

From Barron's ● Aug. 17, 2026

A Shropshire vicar played a key role in a new two-part BBC documentary featuring Welsh Hollywood actor Michael Sheen's investigation into toxic waste dumps.

From BBC ● Aug. 15, 2026

Energy stocks were toxic to most investors before their 2022 boom.

From MarketWatch ● Aug. 10, 2026

"Our study has revealed for the first time that bacteria supplied with glycerol as a carbon source can convert toxic uranium dissolved in water into a stable chemical compound," says Krawczyk-Bärsch.

From Science Daily ● Aug. 9, 2026

Others, such as pulses and members of the mustard family, have toxic seeds, but the toxins are easily removed, leaving the seeds edible.

From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond

The others include rules governing mercury and air toxics; polymers and resins; rubber tires; copper smelting; and coal power, among others.

From Los Angeles Times ● Aug. 16, 2025

"Both in Spokane and New York City, regardless of the setting -- how large or small the cities are -- these air toxics appear to be influencing asthma among children," she said.

From Science Daily ● Mar. 13, 2024

Most of these toxics are lipophilic, stored in fats and blubber, and they really start circulating when mothers have less to eat, Weiss said.

From Seattle Times ● Jan. 29, 2024

Lawn equipment also contributed to a litany of other air toxics, such as formaldehyde and benzene.

From Salon ● Nov. 1, 2023

We expanded every community's right to know about toxics that threaten their children.

From State of the Union Address by William Jefferson Clinton

Related Words

• deadly
• harmful
• lethal
• noxious
• pernicious
• virulent