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.
The attack, which only killed the bomber but could have been much worse, is an act worthy of perhaps the dumbest and most poisonous ideology on the planet right now. Rich Lowry, National Review, 19 May 2025 From such small radioactive acorns do poisonous oaks grow. Adam Gopnik, New Yorker, 19 May 2025 According to the McGill University office for science and society, several species of poison dart frogs contain such powerful toxins in their body that can kill an adult human by just brushing against its poisonous skin. Maria Azzurra Volpe, MSNBC Newsweek, 14 May 2025 Residents near the area were later found to have usually high levels of the poisonous metal in their urine, according to the report. Kiki Intarasuwan, CBS News, 14 May 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 29 May. 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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