poisonous
Americanadjective
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full of or containing poison.
poisonous air; a poisonous substance.
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harmful; destructive.
poisonous to animals; poisonous rumors.
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deeply malicious; malevolent.
poisonous efforts.
adjective
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having the effects or qualities of a poison
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capable of killing or inflicting injury; venomous
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corruptive or malicious
Other Word Forms
Etymology
Origin of poisonous
Compare meaning
How does poisonous compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
What do arsenic, cyanide, and bleach all have in common? They're poisonous. In other words, if you ingest these poisonous chemicals, you will most likely die or become very ill. If something is poisonous, you'd better not eat, drink, inhale, or touch it: it will make you sick. Some poisonous materials can even kill you. Of course, this adjective is derived from the noun poison, which is a toxic substance. You can also calls things poisonous if they're harmful in less physical ways. Spreading lies about someone is poisonous. Betraying a friend is poisonous. What both kinds of poisonous things have in common is that they do damage.
Vocabulary lists containing poisonous
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Harmful, List 2
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-ious, -eous, -ous
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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 this Money Talks: Elizabeth Spiers is joined by psychologist Dr. Leanne ten Brinke whose new book, Poisonous People, explores the impact that people with psychopathic and related personality traits have on our everyday lives.
From Slate • Apr. 14, 2026
Poisonous posts are part of the social media business plan.
From Los Angeles Times • Jul. 21, 2025
She also shared her experiences in her book, Pretty Boys are Poisonous, through two poems.
From BBC • Nov. 12, 2024
Poisonous black smoke pouring in from Jersey marshes.
From New York Times • May 21, 2016
Poisonous plants were growing in the bed just outside the house.
From "Inkheart" by Cornelia Funke
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
