poisonous

adjective

poi·​son·​ous ˈpȯiz-nəs How to pronounce poisonous (audio)
ˈpȯi-zᵊn-əs
1
2
a
: 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
3
poisonously adverb

Examples of poisonous in a Sentence

Chocolate is poisonous to dogs. This species of spider is extremely poisonous.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Gastroenteritis is a good reason to refrain from consuming cocaine, various heavy metals or poisonous mushrooms. Bruce Y. Lee, Forbes.com, 29 July 2025 Then his heart beat its last, and the poisonous moth embraced him. Ingrid Vasquez, People.com, 24 July 2025 And, as Patterson herself testified during the trial, that paste contained death cap mushrooms, which are among the most poisonous in the world. Rachel Treisman, NPR, 7 July 2025 Almost every state has a variety of snake species, both poisonous and nonvenomous. Janet Loehrke, USA Today, 11 July 2025 See All Example Sentences for poisonous

Word History

First Known Use

15th century, in the meaning defined at sense 2

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

Browse Nearby Words

Cite this Entry

“Poisonous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/poisonous. Accessed 7 Aug. 2025.

Kids Definition

poisonous

adjective
poi·​son·​ous ˈpȯiz-nəs How to pronounce poisonous (audio)
-ᵊn-əs
: containing poison : having or causing an effect of poison
poisonously adverb

Medical Definition

poisonous

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

More from Merriam-Webster on poisonous

Last Updated: - Updated example sentences
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