Did you know?
When you hold down the delete key on your keyboard or touchscreen, the effect—whoosh!—is instantaneous. Deleterious effects, however, are often not so obvious; deleterious (ultimately from a Greek word meaning “to hurt”) 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.
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.
Ryan Ermey, CNBC, 1 Apr. 2026
Alcohol, even marijuana, even light marijuana use, can have a deleterious effect on the development of a young brain.
—Stephanie Nolasco, FOXNews.com, 29 Mar. 2026
If signed, municipalities retain some say, with provisions allowing cities to stop plans that present deleterious environmental impacts, health and safety risks, or undue burden on infrastructure like sewer or water.
—Mark Dee
march 28, Idaho Statesman, 28 Mar. 2026
Chicago is a national example of the deleterious impact of this agenda on the national cultural landscape.
—Jane M. Saks, Chicago Tribune, 23 Mar. 2026
See All Example Sentences for deleterious
Cite this Entry
“Deleterious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/deleterious. Accessed 14 Jun. 2026.
Copy CitationKids Definition
deleterious
adjective
Medical Definition
deleterious
adjective
Christine Gorman
