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

But there are dozens of other poisonous snake species for which India does not have targeted antivenom.

From BBC • Feb. 1, 2026

In this poisonous time, those who grin at the notion of playing a Traitor may think twice about the potential cost to their principles.

From Salon • Jan. 28, 2026

But time and again the poisonous isolation that absolute power imposes on its wielders blunted the edge of their insight and degraded the capacity of their societies.

From The Wall Street Journal • Jan. 26, 2026

We watched that big long snake slither away, but luckily it wasn’t poisonous.

From "Lost Boy, Lost Girl" by John Bul Dau

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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