toxicity

noun

tox·​ic·​i·​ty täk-ˈsi-sə-tē How to pronounce toxicity (audio)
plural toxicities
: the quality or state of being toxic: such as
a
: the quality, state, or relative degree of being poisonous
measuring the toxicity level of the soil
The toxicity of some chemical agents degrades significantly over time, so it is unclear how lethal the stockpiles are.David S. Cloud
Administering a cocktail of drugs would dilute the toxicities of the different drugs and minimize the development of viral resistance to them.Rudy M. Baum and Ron Dagani
b
: an extremely harsh, malicious, or harmful quality
In the past few days, I've tuned in to C-SPAN to watch a number of the televised Senate debates, which illustrate all too vividly the toxicity of an uncivil tongue.Connie Schultz
In much of the ensuing commentary, court watchers worried that the justices' soaring rates of written dissents, nasty and personal attacks and scathing remarks read aloud from the bench bespeak a new toxicity in Supreme Court discourse.Dahlia Lithwick

Did you know?

Toxicity is often a relative thing; in the words of a famous old saying, "The dose makes the poison". Thus, it's possible to die from drinking too much water, and lives have been saved by tiny doses of arsenic. Even though botulinum toxin is the most toxic substance known, it's the basic ingredient in Botox, which is injected into the face to get rid of wrinkles. With some poisons, mere skin contact can be lethal; others are lethal when breathed into the lungs in microscopic amounts. To determine if a chemical will be officially called a poison, researchers often use the "LD50" test: If 50 milligrams of the substance for every kilogram of an animal's body weight results in the death of 50% of test animals, the chemical is a poison. But there are problems with such tests, and toxicity remains a very individual concept.

Examples of toxicity in a Sentence

Recent Examples on the Web
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There’s also the risk of secondary toxicity if a mole comes to the surface, dies, and is eaten by a raptor or other predator. Arricca Elin Sansone, Southern Living, 17 Oct. 2025 Historically, Fortune has featured her at its Most Powerful Women platform to discuss online toxicity, civic engagement, and tech accountability, a thread that continues in coverage of her and Prince Harry’s calls for platform policy changes at Meta. Sydney Lake, Fortune, 14 Oct. 2025 The documentary pulled back the curtain on one of Taylor Swift's most vulnerable chapters, capturing her reckoning with fame, body image issues and the pressure to please everyone, while also embracing her voice in LGBTQ+ advocacy and confronting online toxicity. Bryan West, USA Today, 13 Oct. 2025 But during the difficult years, when a horrible cocktail of apathy and toxicity set in, attendance was notably lower. Amy Lawrence, New York Times, 10 Oct. 2025 See All Example Sentences for toxicity

Word History

First Known Use

1873, in the meaning defined above

Time Traveler
The first known use of toxicity was in 1873

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Cite this Entry

“Toxicity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/toxicity. Accessed 20 Oct. 2025.

Medical Definition

toxicity

noun
tox·​ic·​i·​ty täk-ˈsis-ət-ē How to pronounce toxicity (audio)
plural toxicities
: the quality, state, or relative degree of being toxic or poisonous

More from Merriam-Webster on toxicity

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