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

In response to the report, Harriet's parents - Dr Jack and Sarah Hawkins - said the review showed there were significant problems at the hospital where their daughter died, with evidence of a "toxic culture".

From BBC • Jun. 16, 2026

"By improving the pumps, the brain can finally clear out the trapped waste. Over 56 days, the treatment reduced toxic amyloid-beta by 42 percent and improved spatial learning by nearly 44 percent."

From Science Daily • Jun. 16, 2026

Or is he a diva so toxic that his own fans at Real Madrid booed him off the pitch and branded him “a dictator”?

From The Wall Street Journal • Jun. 16, 2026

Three toxic spills from a Barrick Gold mine between 2015 and 2017 contaminated provincial rivers to varying degrees.

From Barron's • Jun. 15, 2026

In 1786, aged just forty-three, he was found dead at his workbench surrounded by an array of toxic chemicals, any one of which could have accounted for the stunned and terminal look on his face.

From "A Short History of Nearly Everything" by Bill Bryson

Related Words

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