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.
Small, everyday ways of being needed — helping a neighbor, being counted on at home, showing up for a team — can buffer against that harmful inner-scorekeeping and build a sturdier sense of self-worth. Jennifer Breheny Wallace, CNBC, 28 Dec. 2025 Perseverance is important, but too stubbornly sticking to initial goals can be harmful. Nicholas Wright, Time, 28 Dec. 2025 Recognizing that a familiar routine may be harmful is the first step toward building healthier habits that support you in the long run. Abby Norman, Verywell Health, 27 Dec. 2025 The Michigan Legislature passed a law in 2008 meant to protect the public from harmful electronic waste toxics. Nushrat Rahman, Freep.com, 27 Dec. 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

Browse Nearby Words

Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 30 Dec. 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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