deleterious
adjective
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When you hold down the delete key on your keyboard or touchscreen, the effect—whoosh!—is instantaneous (unless your device is laggy, of course). Deleterious effects, however, are often not so obvious; deleterious is used to describe things that are harmful in ways that are unexpected, slow-acting, or not readily apparent. Although most often used in formal speech and writing, deleterious is far from rare. It even pops up from time to time in film and television, especially from the mouths of wonky characters, as when Seven of Nine warns the Doctor in an episode of Star Trek Voyager, “The nebula is having a deleterious effect on all the ship’s technology,” or when Higgins exclaims in the original Magnum P.I. series, “It’s shocking what a deleterious effect a regimen of nothing but mushrooms can have on a man.” We’ll take your word for it, Higgins.
Synonyms
Examples of deleterious in a Sentence
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.
Joseph Thorndike, Forbes, 4 Nov. 2024
Accusations of deleterious effects on human health have been investigated and found to be unproven.
—Ian Dexter Palmer, Forbes, 27 Oct. 2024
This turned out to be an apt description of public health experts becoming consumed with preventing COVID-19 transmission through lockdown at the expense of other deleterious social effects.
—Cory Franklin, Chicago Tribune, 11 Oct. 2024
Research into long COVID has highlighted the disease’s deleterious effects on the body’s normal functions over time, and some of the same factors may well be at work here.
—Carolyn Barber, Fortune, 11 Oct. 2024
See all Example Sentences for deleterious 
Dictionary Entries Near deleterious
Cite this Entry
“Deleterious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/deleterious. Accessed 26 Nov. 2024.
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deleterious
adjective
Medical Definition
deleterious
adjective
Christine Gorman
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