noxious

adjective

nox·​ious ˈnäk-shəs 

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

noxiously adverb

noxiousness noun

Synonyms

• insalubrious
• noisome
• sickly
• unhealthful
• unhealthy
• unwholesome

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

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

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

Rhymes for noxious

• obnoxious

Kids 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