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.
Scientists have found bits of plastic in the ocean that are coated in communities of microorganisms, including harmful bacteria.5 Jayakrishnan said the microplastics in the body may play a similar role, offering a medium for cancer-causing bacteria to grow and disrupt the gut microbiome. Claire Bugos, Verywell Health, 7 Mar. 2025 Better yet, they can still be used on public lands to sustain local communities in place of harmful industrial extraction. TIME, 6 Mar. 2025 Cold water can increase blood flow to your face, boosting your skin's protection from free radicals, harmful compounds caused by exposure to UV light and pollution. Sherri Gordon, Health, 6 Mar. 2025 Insecticides have been identified as leading causes of butterfly decline, which can be tackled with policy intervention such as restricting harmful insecticides, promoting integrated pest management and encouraging diversified cropping, according to the study. Sarah Metz, CBS News, 6 Mar. 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 12 Mar. 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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