1
a
: physically harmful or destructive to living beings
noxious waste
noxious fumes
b
: constituting a harmful influence on mind or behavior
especially
: morally corrupting
noxious doctrines
2
: disagreeable, obnoxious
this noxious political scandal—
H. L. Ickes
H. L. Ickes
noxiously
adverb
noxiousness
noun
Examples of noxious in a Sentence
mixing bleach and ammonia can cause noxious fumes that can seriously harm you
noxious smog that for years has been encrusting the historic cathedral with soot
Recent Examples on the Web
Now though, there’s little safe haven in independent art either, where podcasting and comedy have welcomed truly noxious voices that are eager to remake themselves as Wormtongues in the halls of power.
—James Folta
september 19, Literary Hub, 19 Sep. 2025
One of the most noxious of former President Joe Biden’s leftover regulatory rules applies to partnerships — an increasingly common form of business organization and expansion.
—Stephen Moore, Boston Herald, 13 Sep. 2025
Along with the swamp eels, scientists in the USGS Wetland and Aquatic Research Center have been most concerned about the spread of Cuban tree frogs, which secrete noxious chemicals that are harmful to humans, and alligatorweed, which clogs waterways that can impact infrastructure.
—Wesley Bruer, CNN Money, 8 Sep. 2025
With the original Toxic Avenger creator’s blessing, Macon Blair has brought the cult franchise back from its noxious cinematic dumping grounds.
—Glenn Garner, Deadline, 7 Sep. 2025
See All Example Sentences for noxious
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James Folta
september 19, Literary Hub, 19 Sep. 2025
One of the most noxious of former President Joe Biden’s leftover regulatory rules applies to partnerships — an increasingly common form of business organization and expansion.
—Stephen Moore, Boston Herald, 13 Sep. 2025
Along with the swamp eels, scientists in the USGS Wetland and Aquatic Research Center have been most concerned about the spread of Cuban tree frogs, which secrete noxious chemicals that are harmful to humans, and alligatorweed, which clogs waterways that can impact infrastructure.
—Wesley Bruer, CNN Money, 8 Sep. 2025
With the original Toxic Avenger creator’s blessing, Macon Blair has brought the cult franchise back from its noxious cinematic dumping grounds.
—Glenn Garner, Deadline, 7 Sep. 2025
See All Example Sentences for noxious
Cite this Entry
“Noxious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/noxious. Accessed 20 Sep. 2025.
Copy CitationKids Definition
noxious
adjective
nox·ious
ˈnäk-shəs 
: harmful especially to health : unwholesome
noxious fumes
Medical Definition
noxious
adjective
nox·ious
ˈnäk-shəs
: physically harmful or destructive to living beings
noxious wastes
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