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Definitions

harmful

[hahrm-fuhl] / ˈhɑrm fəl /
ADJECTIVE
injurious, hurtful
Synonyms
STRONGEST
adverse bad catastrophic damaging destructive detrimental disadvantageous disastrous inimical noxious painful pernicious risky ruinous sinful toxic unhealthy unsafe
WEAK
baleful baneful calamitous cataclysmic consumptive corroding corrupting crippling deleterious dire evil harassing incendiary internecine malefic malicious malignant menacing mischievous murderous nocuous pestiferous pestilential sinister subversive undermining unwholesome virulent
Antonyms
STRONGEST
advantageous aiding assisting beneficial favorable fortunate good harmless healthy helpful honest kind lucky profitable safe upright

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Oil companies could simply “flare” that gas, allowing it to escape into the air, but that’s harmful to the environment and limited by regulators in most areas.

From Barron's • Apr. 29, 2026

This process creates harmful byproducts that attach small chemical units, known as methyl groups, to DNA.

From Science Daily • Apr. 29, 2026

“You’re not going to earn our votes if you bring somebody who we feel traffics in language that is harmful to us,” he said.

From Slate • Apr. 29, 2026

The obesity drug seems to reduce visceral fat, a harmful form of fat stored around vital organs, the trial showed.

From The Wall Street Journal • Apr. 28, 2026

They could also mean that potentially harmful organisms, formerly held in check, could escape from their natural controls and rise to pest status.

From "Silent Spring" by Rachel Carson

Vocabulary lists containing harmful

Earth Day

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Unfavorable

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