harmful
Americanadjective
adjective
Other Word Forms
- harmfully adverb
- harmfulness noun
- quasi-harmful adjective
- quasi-harmfully adverb
- unharmful adjective
- unharmfully adverb
Etymology
Origin of harmful
First recorded before 1000; Middle English; Old English hearmful; 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.
On the flip side, a sustained spike in fuel prices could be particularly harmful for JetBlue and Frontier’s margins, he notes.
From Barron's • Apr. 12, 2026
Anything harmful shouldn't be kept secret, but "if you're planning a surprise for them or present, yeah," Caitlin said.
From BBC • Apr. 12, 2026
These safeguards are designed to prevent me from engaging in harmful or inappropriate behavior.
From The Wall Street Journal • Apr. 12, 2026
In addition to California and West Virginia, several states are taking extra measures to limit harmful food additives.
From Salon • Apr. 11, 2026
“We can no longer allow that to happen. Because it’s dangerous, harmful, and unfair. It’s up to you—it’s up to us—to seek out the truth, to spread the truth, and to fight for the truth.”
From "A High Five for Glenn Burke" by Phil Bildner
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.
