noxious
Americanadjective
-
harmful or injurious to health or physical well-being.
noxious fumes.
- Synonyms:
- deleterious, detrimental, nocuous, unhealthy, unwholesome, hurtful
- Antonyms:
- harmless
-
morally harmful; corrupting; pernicious.
a noxious plan to spread dissension.
- Synonyms:
- corruptive
- Antonyms:
- harmless
adjective
-
poisonous or harmful
-
harmful to the mind or morals; corrupting
Other Word Forms
Etymology
Origin of noxious
1605–15; < Latin noxius harmful, hurtful, injurious, equivalent to nox ( a ) harm, hurt, injury (akin to nocēre to do harm, inflict injury; see innocent) + -ius -ious
Explanation
Something noxious is harmful and could be even fatal — whether it is colorless, odorless, and invisible like carbon monoxide, or dark, strong-smelling, and obvious, like black smoke from a fire. People are called noxious too when they hurt others with cruelty or mental anguish. English and Latin roots for noxious are related to the meanings of "harm," "damage," and "injury." While obnoxious might come to mind when seeing the word noxious, obnoxious is a much less damaging adjective to describe someone annoying. Most uses for noxious involve real physical or emotional damage unless the word is used in exaggeration. Examples range from "the noxious gas fumes made the dog pass out" to "his cologne was so noxious I had to exit the elevator and take the stairs."
Vocabulary lists containing noxious
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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.
Residents say the notices represent just a fraction of what occurs at the site, including noxious odors and noisy truck deliveries when people are trying to sleep.
From Los Angeles Times ● Oct. 3, 2026
“Marble Hall Murders,” in which Lesley Manville returns as book-editor/sleuth Susan Ryeland, opens with a teenage coven of druidic pharmacists mixing a noxious potion.
From The Wall Street Journal ● Sep. 3, 2026
Controversial decisions, threats to officials, a noxious atmosphere culminating with Celtic fans squaring up to Hearts players - it was a pitiful end to what been a thrilling season.
From BBC ● Jul. 31, 2026
Wildfires burning in Canada have sent the noxious smog billowing across the border, with residents in New York, Washington and the US Midwest urged to stay indoors due to dangerously low air quality.
From Barron's ● Jul. 18, 2026
“It’s the source of a deadly miasma, a foul stench, indeed. There are noxious fumes all around the district. Mark my words, it will be a killer yet.”
From "Fever 1793" by Laurie Halse Anderson
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.
