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.
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
The answer can be found at open dumping sites across Tangerang, including in the areas surrounding the actual landfill, which have precipitated the growth of noxious trash mountains within a hundred metres of people's homes.
From BBC ● Jul. 8, 2026
“It’ll certainly be smelly and noxious, and bacteria and things are going to be growing in it,” he said.
From Los Angeles Times ● Jun. 21, 2026
"So, they can cope with higher levels of noxious irritants produced by cold exposure."
From Science Daily ● Mar. 26, 2026
Clean up the patient and sickroom to remove noxious odors.
From "An American Plague: The True and Terrifying Story of the Yellow Fever Epidemic of 1793" by Jim Murphy
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.
