as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
Something more insidious is at play with all of the half-baked or made-up statistics.
—
Lisa Jarvis, Mercury News, 6 June 2025
The tariff con is particularly insidious because it's sold as economic nationalism while actually functioning as a tax increase on American consumers.
—Nicholas Creel, MSNBC Newsweek, 30 June 2025
There are hundreds, if not thousands, of reasons at the root of that insidious process.
—Guy Martin, Forbes.com, 27 June 2025
As something of a companion piece to More, Jacques Deray’s summer thriller La Piscine is a far more dramatic and insidious tale of tropical desire, lassitude, and violence.
—Erik Morse, Vogue, 26 June 2025
See All Example Sentences for insidious
Lisa Jarvis, Mercury News, 6 June 2025
The tariff con is particularly insidious because it's sold as economic nationalism while actually functioning as a tax increase on American consumers.
—Nicholas Creel, MSNBC Newsweek, 30 June 2025
There are hundreds, if not thousands, of reasons at the root of that insidious process.
—Guy Martin, Forbes.com, 27 June 2025
As something of a companion piece to More, Jacques Deray’s summer thriller La Piscine is a far more dramatic and insidious tale of tropical desire, lassitude, and violence.
—Erik Morse, Vogue, 26 June 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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At least three people were killed in the treacherous flood waters streaming through a mountain village in New Mexico, which also knocked an entire home from its foundations and then swept it away.—
Jessica Schladebeck,
New York Daily News,
9 July 2025
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The search has been complicated by treacherous terrain, and the fact that crews are looking for an Army veteran skilled in wilderness survival who had a three-day head start.—
Cindy Von Quednow,
CNN Money,
7 July 2025
Adjective
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They are intended to reduce trauma to the scalp, may contribute to smoother recovery, and are designed to help achieve subtle, natural-looking outcomes.—
Daniel Fusch,
USA Today,
12 July 2025
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The accessory was a subtle nod to the All England Lawn Tennis and Croquet Club, whose colors have been green and purple since 1909.—
Renan Botelho,
Footwear News,
12 July 2025
Adjective
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He’s hosted several world leaders for explosive Oval Office sit downs, including South African President Cyril Ramaphosa, who Trump argued with over false claims that white farmers in the country were victims of a genocide, and Ukrainian President Volodymyr Zelenskyy in February.—
Sara Dorn,
Forbes.com,
16 July 2025
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In November 2009, Richard pleaded guilty to the latter charge, while Mayumi pleaded guilty to a misdemeanor charge of false reporting to authorities, per CNN.—
EW.com,
EW.com,
15 July 2025
Adjective
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The suit alleges excessive fees resulting in high annual percentage rates, deceptive tipping practices and misleading consumers about the voluntary nature of fees.—
AJ Dhaliwal,
Forbes.com,
9 July 2025
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Mayes seeks to dissolve both companies, citing violations of the Arizona Consumer Fraud Act and deceptive practices targeting underage customers.—
Jose R. Gonzalez,
AZCentral.com,
9 July 2025
Adjective
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Those voting for it are Sean Elo-Rivera, Jennifer Campbell, Kent Lee, Stephen Whitburn, Vivian Moreno and La Jolla’s own Joe LaCava, who has been an active supporter of this perfidious plan.—
Inga,
San Diego Union-Tribune,
16 June 2025
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Jake Gyllenhaal is his foil as the perfidious Iago, who goads Othello into unreasoning jealousy with lies about his beloved Desdemona (Molly Osborne).—
New York Times,
New York Times,
17 Feb. 2025
Adjective
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Rumors the man lost a limb are incorrect, friends of the victim with Raw Surf posted on the business' Facebook page.—
Natalie Neysa Alund,
USA Today,
8 July 2025
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An online commercial real estate site, LoopNet.com, still showed the theater property as up for auction Thursday, but Robinson said the listing is incorrect.—
Phil Diehl,
San Diego Union-Tribune,
6 July 2025
Adjective
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For instance, Putignano says there’s nothing wrong with expecting a teen to clean their room, just as your parents expected of you.—
Beth Ann Mayer,
Parents,
15 July 2025
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There is nothing wrong with having adapted in this way.—
Mark Travers,
Forbes.com,
15 July 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 21 Jul. 2025.
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