poisonous

adjective

poi·​son·​ous ˈpȯiz-nəs 

ˈpȯi-zᵊn-əs

1

: destructive, harmful

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

: spiteful, malicious

poisonously adverb

Synonyms

• envenomed
• poison
• poisoned
• toxic
• venomous

Examples of poisonous in a Sentence

Chocolate is poisonous to dogs.

This species of spider is extremely poisonous.

Recent Examples on the Web

This genus is primarily known for its small but brightly colored amphibian species that are highly poisonous, most notably, the bright orange pumpkin toadlets, B. rotenbergae, B. ephippium and B. pitanga (more here). —Grrlscientist, Forbes, 1 Nov. 2024

Its most frightening aspect, though, is probably its poisonous bite. —Paul Smaglik, Discover Magazine, 22 Oct. 2024

But social media and polarized politics are exposing it at industrial scale, fueled by a poisonous cocktail of bad actors, media illiteracy and plummeting trust in traditional news. —Zachary Basu, Axios, 19 Oct. 2024

Craddock writes this because it was variously believed that the spirit was medicinal (nope), poisonous (not especially) or hallucinogenic (not even close). —Jason O'Bryan, Robb Report, 12 Oct. 2024

Word History

First Known Use

15th century, in the meaning defined at sense 2

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 

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