poi·​son·​ous | \ ˈpȯiz-nəs How to pronounce poisonous (audio) , 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



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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 Iguanas are not poisonous and typically run when a human approaches. NBC News, 2 June 2021 Under the watchful eye of Supreme Leader Ayatollah Ali Khamenei, the nuclear program didn’t fall prey to Iran’s poisonous domestic politics. Ray Takeyh, WSJ, 10 Dec. 2020 The dino has infrared vision perfect for tracking its prey and poisonous stingers — the latter stemming from scorpionfish DNA. Nick Romano, EW.com, 23 May 2021 This will help prevent him from munching on these poisonous flowers. Jennifer Nelson, Southern Living, 14 May 2021 In many ways, this series is a robust act of defusal, an attempt to swat down explosive sensationalism in the service of figuring out the cool hard facts of a matter and showing how quiet and mundane the poisonous effects of The Big Lie can be. Nicholas Quah, Vulture, 13 May 2021 Some kind of poisonous potion that relieves your grief. Brenna Ehrlich, Rolling Stone, 12 May 2021 These poisonous portraits bear little resemblance to the industrious, worried, frugal, devoted and self-reliant woman who emerges from my research as a professor of history and women’s studies. Martha Saxton, The Conversation, 7 May 2021 The decision seems unlikely to quell concerns raised in public and by lawmakers about Facebook’s power, and willingness, to distribute poisonous content worldwide. Michael Hiltzik, Los Angeles Times, 5 May 2021

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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Time Traveler for poisonous

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

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Statistics for poisonous

Last Updated

8 Jun 2021

Cite this Entry

“Poisonous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/poisonous. Accessed 13 Jun. 2021.

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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 How to pronounce poisonous (audio) \

Kids Definition of poisonous

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


poi·​son·​ous | \ ˈpȯiz-nəs, -ᵊn-əs How to pronounce poisonous (audio) \

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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