adjective del·e·te·ri·ous \ ˌde-lə-ˈtir-ē-əs \
Updated on: 11 Jan 2018

Definition of deleterious

: harmful often in a subtle or unexpected way
  • deleterious effects
  • deleterious to health





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Examples of deleterious in a Sentence

  1. In developing countries, the imposition of boundaries around national parks and protected areas has been deleterious for both people and wildlife. —Kristin B. GuntherAssociation of American Geographers2002
  2. 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 FinleyAlbany (New York) Times-Union2 Sept. 1998
  3. 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. RotbergEducation Week9 Mar. 1994
  4. 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 ParkSmithsonianJanuary 1987
  5. The chemical is deleterious to the environment.

  6. The drug has no deleterious effects on patients.

Recent Examples of deleterious from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'deleterious.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of deleterious

Greek dēlētērios, from dēleisthai to hurt

Synonym Discussion of deleterious

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

DELETERIOUS Defined for English Language Learners



Definition of deleterious for English Language Learners

  • : damaging or harmful

Medical Dictionary


adjective del·e·te·ri·ous \ ˌdel-ə-ˈtir-ē-əs \

medical Definition of deleterious

: harmful often in a subtle or an unexpected way
  • the deleterious effects of radiation and chemotherapy on the marrow
  • —Christine Gorman
  • deleterious genes

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nourishment or food and drink

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