harmful
Americanadjective
adjective
Other Word Forms
Derived Forms
Etymology
Origin of harmful
First recorded before 1000; Middle English; Old English hearmful; see harm, -ful
Explanation
Things that are harmful hurt people, or are likely to hurt them. Listening to loud music through headphones can be harmful to your hearing. Harmful is an adjective that comes in handy when you're talking about things that cause injury to someone or damage something. Burning coal can be harmful to the environment, and eating too much candy can be harmful for your teeth. Harmful words can hurt someone's feelings and harmful actions might put them in danger. The Old English hearm, "hurt, evil, or grief," is at the root of harmful.
Vocabulary lists containing harmful
Earth Day
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Unfavorable
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Insurers have long said that their preapproval requirements aim to ensure that patients don’t get unnecessary or harmful care.
From The Wall Street Journal • Jun. 11, 2026
Situations such as concerts, sporting events, fireworks displays, and power tool use can all expose people to potentially harmful noise levels.
From Science Daily • Jun. 10, 2026
The text of the newly proposed Bill C-34 lists seven categories of "harmful content", which includes material bullying a child, or that foments hatred, or incites violence.
From BBC • Jun. 10, 2026
In addition to the social media ban, the new law would also regulate increasingly ubiquitous AI chatbots by requiring companies to "mitigate the risk of the chatbot communicating harmful content."
From Barron's • Jun. 10, 2026
This continental difference in harmful germs resulted paradoxically from the difference in useful livestock.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
