poisonous
Americanadjective
-
full of or containing poison.
poisonous air; a poisonous substance.
-
harmful; destructive.
poisonous to animals; poisonous rumors.
-
deeply malicious; malevolent.
poisonous efforts.
adjective
-
having the effects or qualities of a poison
-
capable of killing or inflicting injury; venomous
-
corruptive or malicious
Other Word Forms
- nonpoisonous adjective
- nonpoisonously adverb
- nonpoisonousness noun
- poisonously adverb
- poisonousness noun
- semipoisonous adjective
- semipoisonously adverb
- unpoisonous adjective
- unpoisonously adverb
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
Week 4 Vocabulary
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Harmful, List 2
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
-ious, -eous, -ous
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
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
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
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
Hydrogen cyanide, which is highly poisonous, can freeze into crystals at low temperatures.
From Science Daily • Jan. 16, 2026
“Conor O’Malley,” he said, his voice growing poisonous now.
From "A Monster Calls" by Patrick Ness
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.
