Synonyms of deleterious

deleterious

adjective

ˌde-lə-ˈtir-ē-əs 

as in harmful

causing or capable of causing harm

nicotine has long been recognized as a deleterious substance

Synonyms & Similar Words

• harmful
• detrimental
• adverse
• damaging
• dangerous
• bad
• injurious
• hazardous
• pernicious
• poisonous
• baneful
• infectious
• prejudicial
• noxious
• evil
• hurtful
• baleful
• mischievous
• wicked
• ill
• nocuous
• destructive
• hostile
• deadly
• lethal
• unsafe
• infective
• inimical
• venomous
• sinister
• insidious
• risky
• unfriendly
• threatening
• ominous
• fatal
• contagious
• perilous
• menacing
• malignant
• unhealthful
• pestiferous
• pestilential
• unhealthy
• unwholesome
• ruinous
• unsound
• pestilent
• killer
• parlous
• nasty
• imperiling
• jeopardizing
• noisome

Antonyms & Near Antonyms

• beneficial
• benign
• harmless
• innocuous
• safe
• useful
• innocent
• advantageous
• favorable
• inoffensive
• good
• propitious
• salutary
• healthful
• healthy
• helpful
• anodyne
• wholesome
• remedial
• curative
• salubrious
• palliative
• sound
• hurtless
• secure
• benignant
• nontoxic
• noninfectious
• nonlethal
• nondestructive
• noncorrosive
• nonpoisonous
• nonfatal
• nonpolluting
• nonvenomous

Synonym Chooser

How is the word deleterious different from other adjectives like it?

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

When is baneful a more appropriate choice than deleterious?

The synonyms baneful and deleterious are sometimes interchangeable, but baneful implies injury through poisoning or destroying.

the baneful notion that discipline destroys creativity

When would detrimental be a good substitute for deleterious?

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

When can noxious be used instead of deleterious?

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

Where would pernicious be a reasonable alternative to deleterious?

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

Example Sentences

Recent Examples of deleterious

But the volatility between our two nations has had other deleterious consequences for our economy. —S.e. Cupp, New York Daily News, 21 Aug. 2025

Anesthetics are powerful and can impart lasting deleterious effects, particularly on the very young and the elderly. —Big Think, 20 Aug. 2025

The Fourth Estate is under attack on many fronts, from the deleterious effects of social media to conspiracy-theory-mongers on the left and right. —Cynthia Littleton, Variety, 15 Aug. 2025

Once considered a disease largely confined to the developed world, the deleterious effects of dementia are now apparent throughout the globe, as life expectancy increases in many formerly developing countries. —Anand Kumar, The Conversation, 7 Aug. 2025

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