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

A 2022 paper also identified higher levels of toxic metals associated with crude oil in the nail clippings of people living near the site.

From Los Angeles Times ● Oct. 3, 2026

I don’t think it’s just toxic for children—we should also focus on adults.

From Slate ● Sep. 29, 2026

In the track, Swift warns a woman about her partner, with whom the singer had a toxic relationship.

From Barron's ● Sep. 28, 2026

Going into the New York sewer system is both illegal and dangerous, officials have said, cautioning that there is a risk of toxic gases and flooding in a confined space.

From BBC ● Sep. 25, 2026

Although we know that the chemicals have almost certainly undergone change during the long period of transit, we do not know whether the altered chemical is more toxic than the original or less.

From "Silent Spring" by Rachel Carson

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

The researchers drew on data collected and modeled by the Environmental Protection Agency on air toxics present in individual neighborhoods surrounding 10 Spokane elementary schools.

From Science Daily ● Mar. 13, 2024

The amount of toxics these females have circulating to pass on to their children through gestation and lactation is partially dependent on their nutritional state.

From Seattle Times ● Jan. 29, 2024

Lawn equipment also contributed to a litany of other air toxics, such as formaldehyde and benzene, according to the report, which is titled “Lawn Care Goes Electric.”

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