Definitions

poisonous

[poi-zuh-nuhs] / ˈpɔɪ zə nəs /

ADJECTIVE

harmful

Synonyms

STRONGEST

dangerous deadly destructive fatal lethal noxious pernicious toxic venomous vicious virulent

WEAK

bad baleful baneful corrupt corruptive deleterious detrimental evil hurtful infective malicious malignant mephitic miasmatic morbid mortal nocuous noisome peccant pestiferous pestilential poison septic toxicant toxiferous viperous

Antonyms

STRONGEST

gentle good harmless healthful healthy helpful kind life-giving nice nonpoisonous wholesome

WEAK

benevolent non-toxic

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

In a typical year, the California Poison Control System may receive up to five reported illnesses linked to poisonous mushrooms, according to authorities.

From Los Angeles Times • May 30, 2026

"The idea is to divide Russia from the outside world," says columnist Andrei Kolesnikov, from opposition outlet Novaya Gazeta, because of the belief that "this world is poisonous to the brains of Russians".

From BBC • Apr. 24, 2026

Unicorn horns can make poisonous water safe to drink, while a griffin’s feather can restore sight.

From The Wall Street Journal • Apr. 16, 2026

It’s got poisonous lead in it from paint.

From Salon • Mar. 6, 2026

It was too far to swim to through the poisonous flood.

From "I Survived Hurricane Katrina, 2005" by Lauren Tarshis

Vocabulary lists containing poisonous

Week 4 Vocabulary

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Harmful, List 2

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-ious, -eous, -ous

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