noxious

adjective

nox·​ious ˈnäk-shəs How to pronounce noxious (audio)
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 scandalH. L. Ickes
noxiously adverb
noxiousness noun
Choose the Right Synonym for noxious

pernicious, baneful, noxious, deleterious, detrimental mean exceedingly harmful.

pernicious implies irreparable harm done through evil or insidious corrupting or undermining.

the claim that pornography has a pernicious effect on society

baneful implies injury through poisoning or destroying.

the baneful notion that discipline destroys creativity

noxious applies to what is both offensive and injurious to the health of a body or mind.

noxious chemical fumes

deleterious applies to what has an often unsuspected harmful effect.

a diet found to have deleterious effects

detrimental implies obvious harmfulness to something specified.

the detrimental effects of excessive drinking

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Latest projections for UConn’s Liam McNeeley before NBA Draft Combine; Samson Johnson receiving buzz Latest projections for UConn's Liam McNeeley before NBA Draft Combine; Samson Johnson receiving buzz Battle against CT weed known as ‘most noxious, invasive’ ever hits trouble. Dom Amore, Hartford Courant, 12 May 2025 Missing this chance would mean even more noxious uses separating the harbor from adjacent communities, continuing to burden them with environmental harm. Tiffany-Ann Taylor, New York Daily News, 5 May 2025 Both Alito and Chief Justice John Roberts, meanwhile, appeared to think that there is something particularly noxious about exposing young people to books with gay characters. Ian Millhiser, Vox, 22 Apr. 2025 The lawsuit claims Eco-Vista has failed to prevent noxious odors and leachate from their trash disposal operation from invading the neighboring homes, interfering with the ability of residents to use and enjoy their homes and property and reducing property values in the area. Ron Wood, Arkansas Online, 22 Apr. 2025 See All Example Sentences for noxious

Word History

Etymology

Middle English noxius, borrowed from Latin noxius "guilty, delinquent, harmful, injurious" (derivative of noxa "injurious behavior, harm, mischief") + -us -ous; noxa derivative (perhaps with -s- as a desiderative suffix) from the base of nocēre "to damage (things), injure, harm (persons)," going back to Indo-European *noḱ-éi̯e- "destroy" (with semantic weakening in Latin), whence also Sanskrit nāśáyati "(s/he) destroys," causative derivatives from a verbal base *neḱ- "disappear, pass out of existence, perish," whence, with varying ablaut grades, Sanskrit náśyati "(s/he) is lost, perishes," Avestan nąsat̰ "has gone away, is lost," Tocharian B näk- "destroy," (in middle voice) "disappear, be destroyed"

Note: The Indo-European verbal base *neḱ- is also the source of a root noun attested as Latin nec-, nex "violent death, killing"; see necro-.

First Known Use

15th century, in the meaning defined at sense 1a

Time Traveler
The first known use of noxious was in the 15th century

Browse Nearby Words

Cite this Entry

“Noxious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/noxious. Accessed 23 May. 2025.

Kids Definition

noxious

adjective
nox·​ious ˈnäk-shəs How to pronounce noxious (audio)
: harmful especially to health : unwholesome
noxious fumes

Medical Definition

noxious

adjective
nox·​ious ˈnäk-shəs How to pronounce noxious (audio)
: physically harmful or destructive to living beings
noxious wastes

More from Merriam-Webster on noxious

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