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.
The first phase of the mussel challenge is written proposals to describe a novel, non-harmful method for dealing with the mussels and boat inspections. Dinah Voyles Pulver, USA Today, 3 May 2026 And for that reason, hormonal contraception has in recent years been presented as a harmful disruptor of the natural joys of womanhood. Andréa Becker, The Atlantic, 3 May 2026 Jackson and other experts detail why apple cores and other food waste are harmful, and why the best way to protect our natural habitats is not to throw anything out, even the seemingly harmless bits. Emily Hayes, Martha Stewart, 2 May 2026 Importantly, the cops noted that Grok generated the harmful images from September 2025 through March 2026, well after X claimed that the functionality had been removed. Ashley Belanger, ArsTechnica, 1 May 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

Browse Nearby Words

Cite this Entry

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

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

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