deleterious
adjective
del·e·te·ri·ous ˌde-lə-ˈtir-ē-əs 
: harmful often in a subtle or unexpected way
deleterious effects
deleterious to health
deleteriously adverb
deleteriousness noun
Synonyms
- adverse
- bad
- baleful
- baneful
- damaging
- dangerous
- detrimental
- evil
- harmful
- hurtful
- ill
- injurious
- mischievous
- nocuous
- noxious
- pernicious
- prejudicial
- wicked
See all Synonyms & Antonyms 
Example Sentences
In developing countries, the imposition of boundaries around national parks and protected areas has been deleterious for both people and wildlife. 
Kristin B. Gunther, Association of American Geographers, 2002 Most everyone now knows the action of pressing mouse keys is far more deleterious to the tender structures of the wrist and hand than typing is. Michael Finley, Albany (New York) Times-Union, 2 Sept. 1998 This skewed allocation of resources away from those most in need, in turn, insures that many young people from low-income families will continue to be shut out of the economy, with obvious deleterious family and social consequences. Iris C. Rotberg, Education Week, 9 Mar. 1994 For as James Keirans pointed out to me, ticks are the world's most notorious carriers of the agents of diseases that strike animals, wild and domestic. And they rank second only to mosquitoes in their deleterious effect on humans. Edwards Park, Smithsonian, January 1987 The chemical is deleterious to the environment. The drug has no deleterious effects on patients. See More
Kristin B. Gunther, Association of American Geographers, 2002 Most everyone now knows the action of pressing mouse keys is far more deleterious to the tender structures of the wrist and hand than typing is. Michael Finley, Albany (New York) Times-Union, 2 Sept. 1998 This skewed allocation of resources away from those most in need, in turn, insures that many young people from low-income families will continue to be shut out of the economy, with obvious deleterious family and social consequences. Iris C. Rotberg, Education Week, 9 Mar. 1994 For as James Keirans pointed out to me, ticks are the world's most notorious carriers of the agents of diseases that strike animals, wild and domestic. And they rank second only to mosquitoes in their deleterious effect on humans. Edwards Park, Smithsonian, January 1987 The chemical is deleterious to the environment. The drug has no deleterious effects on patients. See More Recent Examples on the Web While tariffs may be a hypothetical future bargaining chip, the deleterious impact of such tariffs on a U.S. economy in crisis is already being felt across the board. Jason Oxman, Fortune, 19 July 2022 Death has a more deleterious impact on the environment than many realize. William Ralston, Wired, 26 July 2022 Such high quit rates have become so deleterious that companies are flagging the Great Resignation as a potential business risk in their annual reports. Phil Wahba, Fortune, 28 Apr. 2022 The Defense Department suggests that the lack of in-person engagement throughout the pandemic has had a deleterious effect on recruiting; that seems more plausible. WSJ, 4 Aug. 2022 But the rise of benzos has also had deleterious effects in a country that is still in the grips of a deadly opioid epidemic. Julyssa Lopez, Rolling Stone, 5 July 2022 The people who might most benefit from this book—those who have bought into the myth of paradise with an ocean view, deleterious impact be damned, and have the means to regularly experience a version of it—don’t want their illusions destroyed. Lauren Groff, The Atlantic, 21 June 2022 There is a hot debate about the effects of using ethanol blends above 10%, but apparently 15% does not have a deleterious impact on engines—at least four stroke engines. Michael Lynch, Forbes, 6 June 2022 In the late 1950s, after experiencing antisemitism in his own life and seeing its deleterious impact on society, Schary went on to become national chairman of ADL. Jonathan Greenblatt, The Hollywood Reporter, 21 Mar. 2022 See More
Jason Oxman, Fortune, 19 July 2022 Death has a more deleterious impact on the environment than many realize. William Ralston, Wired, 26 July 2022 Such high quit rates have become so deleterious that companies are flagging the Great Resignation as a potential business risk in their annual reports. Phil Wahba, Fortune, 28 Apr. 2022 The Defense Department suggests that the lack of in-person engagement throughout the pandemic has had a deleterious effect on recruiting; that seems more plausible. WSJ, 4 Aug. 2022 But the rise of benzos has also had deleterious effects in a country that is still in the grips of a deadly opioid epidemic. Julyssa Lopez, Rolling Stone, 5 July 2022 The people who might most benefit from this book—those who have bought into the myth of paradise with an ocean view, deleterious impact be damned, and have the means to regularly experience a version of it—don’t want their illusions destroyed. Lauren Groff, The Atlantic, 21 June 2022 There is a hot debate about the effects of using ethanol blends above 10%, but apparently 15% does not have a deleterious impact on engines—at least four stroke engines. Michael Lynch, Forbes, 6 June 2022 In the late 1950s, after experiencing antisemitism in his own life and seeing its deleterious impact on society, Schary went on to become national chairman of ADL. Jonathan Greenblatt, The Hollywood Reporter, 21 Mar. 2022 See More Word History
Etymology
Greek dēlētērios, from dēleisthai to hurt
First Known Use
1587, in the meaning defined above
Medical Definition
deleterious
adjective
del·e·te·ri·ous ˌdel-ə-ˈtir-ē-əs
: harmful often in a subtle or an unexpected way
the deleterious effects of radiation and chemotherapy on the marrow Christine Gorman
Christine Gormandeleterious genes
deleterious
adjective
as in detrimental
causing or capable of causing harm nicotine has long been recognized as a deleterious substance Synonyms & Similar Words
Relevance
- detrimental
- harmful
- adverse
- damaging
- dangerous
- bad
- injurious
- pernicious
- hazardous
- baneful
- poisonous
- noxious
- prejudicial
- hurtful
- infectious
- evil
- baleful
- nocuous
- destructive
- mischievous
- ill
- wicked
- hostile
- deadly
- lethal
- inimical
- infective
- unsafe
- insidious
- venomous
- sinister
- risky
- unfriendly
- threatening
- pestiferous
- pestilential
- ominous
- fatal
- pestilent
- unhealthful
- perilous
- malignant
- unwholesome
- unhealthy
- contagious
- menacing
- ruinous
- imperiling
- unsound
- jeopardizing
- parlous
- nasty
- imperilling
- noisome
- killer
Antonyms & Near Antonyms
- beneficial
- harmless
- benign
- innocuous
- advantageous
- useful
- innocent
- safe
- favorable
- inoffensive
- anodyne
- good
- salutary
- healthful
- propitious
- healthy
- salubrious
- curative
- wholesome
- remedial
- helpful
- palliative
- sound
- hurtless
- secure
- benignant
- nontoxic
- noninfectious
- nonlethal
- noncorrosive
- nonpoisonous
- nondestructive
- nonfatal
- nonpolluting
- nonvenomous
Synonym Chooser
Some common synonyms of deleterious are baneful, detrimental, noxious, and pernicious. While all these words mean "exceedingly harmful," deleterious applies to what has an often unsuspected harmful effect.
a diet found to have deleterious effects
The synonyms baneful and deleterious are sometimes interchangeable, but baneful implies injury through poisoning or destroying.
the baneful notion that discipline destroys creativity
The words detrimental and deleterious are synonyms, but do differ in nuance. Specifically, detrimental implies obvious harmfulness to something specified.
the detrimental effects of excessive drinking
The meanings of noxious and deleterious largely overlap; however, noxious applies to what is both offensive and injurious to the health of a body or mind.
noxious chemical fumes
The words pernicious and deleterious can be used in similar contexts, but pernicious implies irreparable harm done through evil or insidious corrupting or undermining.
the claim that pornography has a pernicious effect on society