poisonous

adjective

poi·son·ous ˈpȯiz-nəs

ˈpȯi-zᵊn-əs

Synonyms of poisonous

: destructive, harmful

: having the properties or effects of poison

poisonous gas

: producing a toxic substance that causes injury or death when absorbed or ingested

poisonous mushrooms

also : venomous

a poisonous spider

: spiteful, malicious

poisonous rumors

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.

This low-temperature, low-pressure hydrometallurgical method removes arsenic cleanly and operates without fossil fuels or poisonous gas emissions. — Mrigakshi Dixit, Interesting Engineering, 19 Oct. 2026 This may allow poisonous rat boxes to be on the street for less time. — Mike Sullivan, CBS News, 16 Oct. 2026 With the throne disengaged from governance, petitions and reports from officials piled up unread, crucial state posts went unfilled, and the imperial bureaucracy splintered amid poisonous factional infighting. — Carl Minzner, Foreign Affairs, 5 Oct. 2026 With this potential even more poisonous investments in the bloated and indebted Paramount behemoth, there’s even more reason to reject it. — Abigail Disney, New York Daily News, 28 Sep. 2026 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

See more words from the same century

Browse Nearby Words

poison oak

poisonous

poison out

See all Nearby Words

Cite this Entry

Style

“Poisonous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/poisonous. Accessed 22 Oct. 2026.

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Kids Definition

poisonous

adjective

poi·son·ous ˈpȯiz-nəs

-ᵊn-əs

: containing poison : having or causing an effect of poison

poisonously adverb

Medical Definition

poisonous

adjective

poi·son·ous ˈpȯiz-nəs, -ᵊn-əs

: having the properties or effects of poison

poisonous gas

: producing a toxic substance that causes injury or death when absorbed or ingested

poisonous frogs and plants

also : venomous

poisonous

adjective

Synonyms of poisonous

Examples of poisonous in a Sentence

Word History

Browse Nearby Words

Cite this Entry

Kids Definition

Medical Definition

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