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.

It’s got poisonous lead in it from paint.

From Salon • Mar. 6, 2026

Hydrogen cyanide, which is highly poisonous, can freeze into crystals at low temperatures.

From Science Daily • Jan. 16, 2026

He was responding to a question from Liberal Democrat leader Sir Ed Davey, who said antisemitism was real, "poisonous" and that "we must all work together to stamp it out".

From BBC • Dec. 17, 2025

Old wives’ tales of silver spoons turning black when they touch a poisonous mushroom, or that only bright-colored or foul-tasting mushrooms are unsafe are false, he said.

From Los Angeles Times • Dec. 10, 2025

I knew it wasn’t poisonous, but I froze.

From "The Teacher’s Funeral" by Richard Peck

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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