harmful

adjective

harm·​ful ˈhärm-fəl How to pronounce harmful (audio)
: of a kind likely to be damaging : injurious
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.
Avocado oil reduces unstable harmful molecules (free radicals) in rodent brains and increases the presence of antioxidant molecules.1 6. Amy Brownstein, Ms, Rdn, Verywell Health, 31 Jan. 2025 Wear sunglasses that block 100% of UVA and UVB rays to protect your eyes from harmful UV exposure, even on cloudy days. Dan Perry, Newsweek, 31 Jan. 2025 But vapor compression still frequently relies on environmentally harmful chemical refrigerants. Andrew Paul, Popular Science, 30 Jan. 2025 Zeldin supported a bill to reduce harmful forever chemicals, called PFAS, that would have required the EPA to set limits on substances in drinking water. CBS News, 29 Jan. 2025 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

Dictionary Entries Near harmful

Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 6 Feb. 2025.

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

More from Merriam-Webster on harmful

Last Updated: - Updated example sentences
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