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.
Health and Safety Concerns Proper ventilation is vital when using bleach because bleach fumes can be harmful if inhaled. Daley Quinn, Southern Living, 1 Nov. 2025 The administration has sown confusion and instability through other means, including harmful funding freezes. Gwen Moore, MSNBC Newsweek, 31 Oct. 2025 The Quince style is dyed without harmful chemicals, giving the pants a one-of-a-kind look. Destinee Scott, Travel + Leisure, 30 Oct. 2025 Lack of any safety warnings on harmful or dangerous content. ​wendy Wisner, Parents, 30 Oct. 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

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Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 4 Nov. 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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