harmful

adjective

ˈhärm-fəl How to pronounce harmful (audio)
Definition of harmfulnext
as in detrimental
causing or capable of causing harm DDT has been proven to be extremely harmful to the environment

Synonyms & Similar Words

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Antonyms & Near Antonyms

Example Sentences

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.
Recent Examples of harmful As a bonus, health-conscious shoppers will love that the fabric is OEKO-TEX certified and free of any harmful substances. — Cheryl Wagemann, InStyle, 29 June 2026 Dogs, however, remain heavily restricted due to high heat and the presence of harmful cyanobacteria and cyanotoxins in the Virgin River. — Rebecca R. Norris, USA Today, 29 June 2026 While much of the contact Clark absorbs during games is real and the calls for more consistent officiating are largely warranted, the implicit and stereotypical framing of these conversations are harmful to the sport. — Lindsey Darvin, Forbes.com, 30 June 2026 The plasma process also produced very little smoke or tar, reducing harmful secondary pollutants typically associated with biomass conversion and making the technology a cleaner way to produce renewable solid fuel. — New Atlas, 1 July 2026 See All Example Sentences for harmful
Recent Examples of Synonyms for harmful
  1. detrimental
  2. damaging
  3. dangerous
  4. adverse
  5. bad
Adjective
  • And beneath the surface of those turquoise waters, marine life continues on without knowing their life is colliding in detrimental-to-them ways.
    — Melissa Cristina Márquez, Forbes.com, 2 July 2026
  • Substance abuse is greatly detrimental in its own right, of course, but sometimes the issues that stem from it—stress, emotional exhaustion, secrecy, avoidance—can have similarly devastating long-term effects on a person’s wellbeing.
    — Kaitlyn Gomez, Miami Herald, 29 June 2026
Definition of detrimental
Adjective
  • Each specimen was weighed and put in the same-sized containers filled with superworm larvae to determine the optimal ratio of larvae to specimen for thorough cleaning without damaging bones.
    — Jennifer Ouellette, ArsTechnica, 1 July 2026
  • And such a gap can be far more damaging than any technology shortfall.
    — Eugenia Mykuliak, Forbes.com, 1 July 2026
Definition of damaging
Adjective
  • Teri handled higher-value finds and saw that potentially dangerous items – like firearms and knives – got to the local sheriff’s office.
    — Alisha Ebrahimji, CNN Money, 6 July 2026
  • Looking back through the sequence, Brazil have good numbers back and there is little need for anyone to overcommit — but a lazy tackle from behind leads to a free kick in a dangerous area.
    — Mark Carey, New York Times, 6 July 2026
Definition of dangerous
Adjective
  • These conditions can increase your vulnerability to adverse effects from poor air quality.
    — Southern California Weather Report, Oc Register, 4 July 2026
  • Valentine also testified that the FDA encourages infant formula companies to send in all adverse event reports and that nothing prevented Mead Johnson from doing so.
    — David Hilzenrath, USA Today, 2 July 2026
Definition of adverse
Adjective
  • That if you were deemed, as an enslaved person, if you were deemed troublesome or in some way unwanted, you would literally be sold down the river from the more northern states to the deeper south where you would potentially be treated even worse.
    — Dana Taylor, USA Today, 3 July 2026
  • Offer Real Value, Not Leftovers Most product bundles fail not because the idea is bad but because the execution misses what consumers actually want.
    — Expert Panel®, Forbes.com, 2 July 2026
Definition of bad

Browse Nearby Words

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harmfulness
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Cite this Entry

“Harmful.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/harmful. Accessed 7 Jul. 2026.

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More from Merriam-Webster on harmful

Nglish: Translation of harmful for Spanish Speakers

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