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

In July of last year Steyer sent out a tweet criticizing rent control for its deleterious and counterproductive effects. —Rafael Perez, Oc Register, 1 Mar. 2026

Conversely, cannabis appears to be especially deleterious to the cognitive and psychological well-being of young people. —Alexander Nazaryan, New Yorker, 29 Jan. 2026

Studies have shown that routine use of AI has a deleterious impact on cognition, creativity, recall, and critical thinking. —Krista Kafer, Denver Post, 25 Jan. 2026

Virtually no one’s immune from their deleterious effects, since they’re found in a wide variety of everyday products. —Editorial, Boston Herald, 11 Jan. 2026