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 mid-May, public health officials in Napa County said three people had been hospitalized after eating poisonous wild mushrooms foraged in the Deer Park community.

From Los Angeles Times • May 30, 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

Whether you have sympathy for him, think his behaviour is appalling, or something in between, there's clearly a poisonous row raging over what he did.

From BBC • Jan. 17, 2026

I feel like she just dropped a seed of doom down my throat and now it’s growing and spreading poisonous vines that are wrapping around my internal organs.

From "Odd One Out" by Nic Stone

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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