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.
In 2022-23, Arteta failed to adapt quickly enough to stop a harmful run of three successive draws in April. Art De Roché, New York Times, 7 Oct. 2025 The tort of battery, meaning unlawful and harmful physical contact, and intentional infliction of emotional distress, which refers to using extreme conduct to terrorize another, are potential claims. Michael McCann, Sportico.com, 6 Oct. 2025 Independent testing confirms that the supplement contains the ingredients listed on the label and is free from harmful contaminants. Kirstyn Hill, Health, 6 Oct. 2025 HFAs aren’t as harmful for the ozone layer as chlorofluorocarbon formulation inhalers that were phased out in the US from 2009 to 2013. Jen Christensen, CNN Money, 6 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

Browse Nearby Words

Cite this Entry

“Harmful.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/harmful. Accessed 7 Oct. 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
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!