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Synonyms
Examples of harmful in a Sentence
DDT has been proven to be extremely harmful to the environment.
Recent Examples on the Web
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
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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
Legal Definition
harmful
adjective
harm·ful
: of a kind likely to cause harm
harmfully
adverb
harmfulness
noun
More from Merriam-Webster on harmful
Nglish: Translation of harmful for Spanish Speakers
Britannica English: Translation of harmful for Arabic Speakers
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