tox·​ic·​i·​ty | \täk-ˈsi-sə-tē \
plural toxicities

Definition of toxicity 

: 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

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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

But with Cota, the company can sign an agreement with the insurer to prove that the test can improve patient outcomes by avoiding unnecessary toxicities from chemotherapy while also keeping costs down. Lindsay Carlton, Fox News, "Data sharing company helps improve cancer patient outcomes, reduce total cost of care," 13 July 2018 Daughters have long been deployed as shields against criticism, human buffers against paternal toxicity. Hannah Giorgis, The Atlantic, "The Trumpian Dissonance of Kanye West's ‘Violent Crimes’," 1 June 2018 Previous research has demonstrated triclosan’s toxicity at doses that would be unusually high for humans, but the new study is among the first to rigorously explore the compound’s safety at more typical levels of exposure. Melissa Healy,, "Triclosan could be really harmful to your gut, and it's probably in your toothpaste," 31 May 2018 Scientists, however, are beginning to unravel why these dangerous toxicities crop up — and are proposing potential interventions that could make CAR-T therapy safer. Meghana Keshavan, STAT, "Research in mice may explain CAR-T therapy’s toxic side effects — and how to block them," 29 May 2018 Since even low amounts of chlorine in water are harmful to aquatic life, dechlorination is required to reduce toxicity in the wastewater discharged to the lake. Don Behm, Milwaukee Journal Sentinel, "MMSD penalizes Veolia Water Milwaukee for discharge violations at Jones Island sewage plant," 27 Mar. 2018 It is considered highly toxic to fish and bees, but low in toxicity to birds, according to the center. Scott Dance,, "Dealing with more bug bites than usual? Mosquitos are at 3 times their normal number in Maryland this summer.," 5 July 2018 As for streaming services, Hulu Tuesday yanked its Roseanne reruns, indicating a level of toxicity likely to deter others. Andrea Mandell, USA TODAY, "What happens to 'Roseanne'? Racist tweet likely Barrs revival elsewhere, even without her," 30 May 2018 The next steps are to scale that production up to hundreds of grams or pounds, Sabatini says, so that full toxicity screenings can be done as well as explosive tests in the field. Jay Bennett, Popular Mechanics, "So Long TNT, There's a New Explosive in Town," 2 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'toxicity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of toxicity

1879, in the meaning defined above

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Last Updated

8 Nov 2018

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Time Traveler for toxicity

The first known use of toxicity was in 1879

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More Definitions for toxicity


tox·​ic·​i·​ty | \täk-ˈsis-ət-ē \
plural toxicities

Medical Definition of toxicity 

: the quality, state, or relative degree of being toxic or poisonous

More from Merriam-Webster on toxicity

Spanish Central: Translation of toxicity

Nglish: Translation of toxicity for Spanish Speakers

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