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

The Select Subcommittee has done its best to contribute to this poisonous miasma. —Michael Hiltzik, Los Angeles Times, 6 June 2024

There was an ominous quality to the stained corduroy couch, a sense that something poisonous lay dormant in its cushions. —Hazlitt, 5 June 2024

These are known to sometimes be mistaken for other poisonous species. —Erin McMullen, TIME, 30 May 2024

But Slovakia’s politics are particularly poisonous, swamped by wild conspiracy theories and bile. —Andrew Higgins, New York Times, 19 May 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