HARMFUL Synonyms: 90 Similar and Opposite Words

harmful

adjective

ˈhärm-fəl

Definition of harmful

as in detrimental

causing or capable of causing harm DDT has been proven to be extremely harmful to the environment

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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 In a number of wrongful death lawsuits, ChatGPT is blamed for driving users to experience harmful delusions and, in some cases, to commit suicide. — Ashley Capoot, CNBC, 14 Oct. 2026 But should there be anybody innocent who’s been accused, that’s harmful too…. — Savannah Walsh, Vanity Fair, 14 Oct. 2026 But if quitting is not immediately achievable, moving away from combustible tobacco may reduce exposure to harmful chemicals in cigarette smoke. — Emma Fenske, The Conversation, 13 Oct. 2026 In theory, a kill switch would allow operators to stop AI agents from such harmful behaviors. — Laurent Belsie, Christian Science Monitor, 13 Oct. 2026 See All Example Sentences for harmful

Recent Examples of Synonyms for harmful

Adjective

Hyperscalers opine on how detrimental electrical outages are to their business.

— Drew Robb, Time, 15 Oct. 2026
Kennon, who is currently being held in Falkenburg Road Jail, was released from the program due to conduct detrimental to the team, the school said.

— Ryan Morik OutKick, FOXNews.com, 14 Oct. 2026

Definition of detrimental

Adjective

Strong overnight thunderstorms brought heavy rain and damaging winds to the Kansas City metro, prompting a tornado warning for Clay County and leaving thousands of people without power Wednesday morning.

— Kansas City Star, Kansas City Star, 14 Oct. 2026
In a culture marked by high-power distance, that’s a particularly damaging signal.

— Ryoji Sekido, Fortune, 13 Oct. 2026

Definition of damaging

Adjective

Swimmers should remain out of the water due to dangerous surf conditions.

— NC Weather Bot, Charlotte Observer, 18 Oct. 2026
Fresh to strong winds will produce dangerous boating conditions, high surf, life-threatening rip currents, and moderate beach erosion through at least the first half of the coming week, forecasters said.

— Felix Rodriguez, The Orlando Sentinel, 18 Oct. 2026

Definition of dangerous

Adjective

In fact, the National Trust for Historic Preservation says the nationwide average for a review is 16 days, and that 98% of those reviews conclude that the project will have no adverse effect on nearby historic resources.

— Rachel Treisman, NPR, 15 Oct. 2026
High prices also a factor But despite positive weather news and whispers of an abundance of crab, other factors could affect prices in adverse ways for consumers.

— Miami Herald, Miami Herald, 15 Oct. 2026

Definition of adverse

Adjective

Bajaria may also have hit thin ice with Sarandos after the streamer won just 16 Primetime Emmy Awards this year — its worst showing since 2016 and down from 30 in 2025.

— Matt Donnelly, Variety, 16 Oct. 2026
The size of the boat, the distance from the tow boat's berth and how bad the boat is stuck will all factor into the final invoice.

— Joe Kinsey OutKick, FOXNews.com, 15 Oct. 2026

Definition of bad

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harmful

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“Harmful.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/harmful. Accessed 21 Oct. 2026.

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Synonyms of harmful

adjective

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