harmful

adjective

harm·​ful ˈhärm-fəl How to pronounce harmful (audio)
Synonyms of harmfulnext
: of a kind likely to be damaging : injurious
harmful chemicals
harmfully adverb
harmfulness noun

Examples of harmful in a Sentence

DDT has been proven to be extremely harmful to the environment.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
While giving users information on how to conduct harmful activities could be concerning, the more worrying part is how the chatbots can egg users on, said Samuel Hunter, senior scientist and director of academic research at NCITE. Huo Jingnan, NPR, 31 May 2026 Respondents see many narrative gaps in storylines, characters, and emotions, with portrayals that too often convey harmful stereotypes. Dominique Fluker, Forbes.com, 30 May 2026 But these arguments, about how free expression is defined, whether art that offends is inherently harmful, and whose sensibilities determine what art gets shown to the public, would recur again and again. Isaac Butler, New Yorker, 30 May 2026 Cans block harmful light better than bottles, whose long necks can allow light and oxygen that speed up aging. Kait Hanson, Southern Living, 29 May 2026 See All Example Sentences for harmful

Word History

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of harmful was in the 14th century

Browse Nearby Words

Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 1 Jun. 2026.

Kids Definition

harmful

adjective
harm·​ful ˈhärm-fəl How to pronounce harmful (audio)
: causing damage : injurious
harmfully adverb
harmfulness noun

Legal Definition

harmful

adjective
harm·​ful
: of a kind likely to cause harm
harmfully adverb
harmfulness noun

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