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
ˈhärm-fə-lē How to pronounce harmful (audio)
adverb
harmfulness noun

Synonyms of harmful

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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.
The administration argues that the new tariffs are necessary to address Canada’s harmful discrimination against the United States auto industry, and are justified by Section 338 of Smoot-Hawley. — Caleb Petitt, Fortune, 2 Aug. 2026 Maxxing involves individuals ignoring the potentially harmful consequences of their actions in pursuit of unrealistic and often thwarted ideals of self-improvement. — Brennan Barnard, Forbes.com, 1 Aug. 2026 And they will undoubtedly be sent to harmful, dangerous situations. — Chiara Eisner, NPR, 1 Aug. 2026 Even natural pesticides can be harmful if ingested or cause allergic reactions, so always follow label instructions. — Nicole Hernandez, USA Today, 1 Aug. 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

Rhymes for harmful

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Browse Nearby Words

harmer
harmful
harmfully
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Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 5 Aug. 2026.

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Kids Definition

harmful

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

Nglish: Translation of harmful for Spanish Speakers

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