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[nok-shuh s] /ˈnɒk ʃəs/
harmful or injurious to health or physical well-being:
noxious fumes.
morally harmful; corrupting; pernicious:
a noxious plan to spread dissension.
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
Related forms
noxiously, adverb
noxiousness, noun
1. hurtful, unwholesome, unhealthy, nocuous, detrimental, deleterious. 2. corruptive.
1, 2. harmless. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for noxious
Contemporary Examples
Historical Examples
  • No, he does not find it; brambles are there and noxious weeds galore.

    The Book of Khalid Ameen Rihani
  • The excreta of that army of sick poisoned the air with their noxious emanations.

    The Downfall Emile Zola
  • At Verdun, along the entire frontier, there were nests of these noxious vermin.

    A Nest of Spies Pierre Souvestre
  • With blood and iron we will ourselves stamp out this noxious breed.

    The Burning Spear John Galsworthy
  • Now it happens that he is noxious to us—let the reasons be what they may.

    St. Martin's Summer Rafael Sabatini
British Dictionary definitions for noxious


poisonous or harmful
harmful to the mind or morals; corrupting
Derived Forms
noxiously, adverb
noxiousness, noun
Word Origin
C17: from Latin noxius harmful, from noxa injury
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for noxious

c.1500, from Latin noxius "hurtful, injurious," from noxa "injury, hurt, damage entailing liability" (related to nocere "to hurt," and to nex "slaughter"), from PIE *nek-ro-, causative form of root *nek- "death" (see necro-).

Online Etymology Dictionary, © 2010 Douglas Harper
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noxious in Medicine

noxious nox·ious (nŏk'shəs)
Harmful to living things; injurious to health.

nox'ious·ness n.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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