poi·son·ous | \ˈpȯiz-nəs, ˈpȯi-zᵊn-əs\

Definition of poisonous 

2a : having the properties or effects of poison poisonous gas

b : producing a toxic substance that causes injury or death when absorbed or ingested poisonous mushrooms also : venomous a poisonous spider

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Other Words from poisonous

poisonously adverb

Synonyms & Antonyms for poisonous


envenomed, poison, poisoned, toxic, venomous


nonpoisonous, nontoxic, nonvenomous

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Examples of poisonous in a Sentence

Chocolate is poisonous to dogs. This species of spider is extremely poisonous.

Recent Examples on the Web

The chaotic and bloody presidential politics of 1968 directly reflected the poisonous effects long-term of the Vietnam War on American society. Arthur I. Cyr, Lake County News-Sun, "Cyr: The essence of Memorial Day," 1 June 2018 It was formed in the aftermath of World War II where there was poisonous nationalism that caused two world wars in the twentieth century that killed more than 100 million people. Fox News, "Meadows, Dershowitz react after Lisa Page defies subpoena," 12 July 2018 The shell of the castor bean is highly poisonous and can be used to make ricin. Eric Schmitt, New York Times, "ISIS May Be Waning, but Global Threats of Terrorism Continue to Spread," 6 July 2018 This is how researchers can look at the koala genome and see how the species is genetically supercharged to digest a plant that’s poisonous to other mammals, namely the cytochrome P450 gene family. Matt Simon, WIRED, "Can the Koala Genome Save the Species From Deforestation and Chlamydia?," 2 July 2018 As the crops grow, the plants incorporate the neonics into their tissues, making them poisonous to any insect that nibbles on them. National Geographic, "Why Europe's Insecticide Ban Is Big News for Bees," 27 Apr. 2018 Just before President Barack Obama left office, the Consumer Product Safety Commission had voted to force the industry to make generators that emit lower levels of the poisonous gas. Juliet Eilperin, chicagotribune.com, "Emails reveal close rapport between top EPA officials and those they regulate," 1 July 2018 Syrian rebels accused government forces on Saturday of dropping a barrel bomb containing poisonous chemicals on civilians in Eastern Ghouta, and a medical relief organization said 35 people were killed in chemical attacks on the area. Washington Post, "World Digest: April 7, 2018," 7 Apr. 2018 Three companies that have purchased crude oil from the United States now claim the oil contained unusually high levels of poisonous chemicals, according to Reuters. David Grossman, Popular Mechanics, "The U.S Sold Contaminated Crude Oil From Its Strategic Reserve—Report," 29 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'poisonous.' 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 poisonous

15th century, in the meaning defined at sense 2

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Statistics for poisonous

Last Updated

8 Oct 2018

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Time Traveler for poisonous

The first known use of poisonous was in the 15th century

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More Definitions for poisonous



English Language Learners Definition of poisonous

: causing sickness or death by entering or touching the body : containing poison

: capable of putting poison into another animal's body by biting it

: very harmful or unpleasant


poi·son·ous | \ˈpȯi-zᵊn-əs \

Kids Definition of poisonous

: containing poison : having or causing an effect of poison poisonous mushrooms


poi·son·ous | \ˈpȯiz-nəs, -ᵊn-əs \

Medical Definition of poisonous 

1 : having the properties or effects of poison poisonous gas

2 : producing a toxic substance that causes injury or death when absorbed or ingested poisonous frogs and plants also : venomous

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Comments on poisonous

What made you want to look up poisonous? Please tell us where you read or heard it (including the quote, if possible).


exaggeratedly or childishly emotional

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