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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Recent Examples of insidious
The surprise that followed was more insidious: a slow and deliberate betrayal in court.
—
Dylan Moore, National Review, 1 Mar. 2025
This gripping series takes viewers into insidious modern-day cults through the unique lens of members who endured unspeakable trauma and the shocking investigations into these oppressive groups.
—Katcy Stephan, Variety, 27 Feb. 2025
Just three strains of this insidious malware threat, Lumma, StealC, and Redline, were responsible for 75% of all infected systems.
—Davey Winder, Forbes, 24 Feb. 2025
Mischaracterized in right-wing media circles, the law has faced backlash indicative of a broader, more insidious narrative: the myth that white South Africans are being systematically targeted for land dispossession and genocide.
—Josh Hammer, Newsweek, 14 Feb. 2025
See All Example Sentences for insidious
Dylan Moore, National Review, 1 Mar. 2025
This gripping series takes viewers into insidious modern-day cults through the unique lens of members who endured unspeakable trauma and the shocking investigations into these oppressive groups.
—Katcy Stephan, Variety, 27 Feb. 2025
Just three strains of this insidious malware threat, Lumma, StealC, and Redline, were responsible for 75% of all infected systems.
—Davey Winder, Forbes, 24 Feb. 2025
Mischaracterized in right-wing media circles, the law has faced backlash indicative of a broader, more insidious narrative: the myth that white South Africans are being systematically targeted for land dispossession and genocide.
—Josh Hammer, Newsweek, 14 Feb. 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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Combined with a light glaze of ice that could fall before temperatures drop, travel in the area could be treacherous that day, the weather service said.—
Sean Murphy and Russ Bynum,
Los Angeles Times,
15 Mar. 2025
-
The legendary Stadium, Mountain, and Dunes courses now have bigger and faster greens as well as more treacherous hazards.—
Passport by ForbesLife,
Forbes,
14 Mar. 2025
Adjective
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Kennedy’s subversion of vaccines, subtle at times, glaring at others, goes far beyond the measles outbreak.—
Nicholas Florko,
The Atlantic,
14 Mar. 2025
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Of course, artists such as Mondrian and Klimt would likely not have been aware of fractals, or the math that underpins them, but perhaps had an innate understanding of the subtle proportions all trees share, according to the researchers.—
Katie Hunt,
CNN,
14 Mar. 2025
Adjective
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Fowler played more of a false nine and dropped deeper to stitch the play together, combining well with Jill Roord.—
Charlotte Harpur,
The Athletic,
20 Mar. 2025
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The pivotal addition to the the state Civil Code reads: Existing law provides that libel is a false and unprivileged written publication that injures the reputation and that slander is a false and unprivileged publication, orally uttered, that injures the reputation, as specified.—
Dominic Patten,
Deadline,
20 Mar. 2025
Adjective
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False Hope And Fake Assurances Ransomware operators also exploit victims with false assurances, creating a deceptive sense of hope that there is a way to resolve the situation.—
Stu Sjouwerman,
Forbes,
10 Mar. 2025
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That’s the film’s greatest surprise, its secret deceptive pitch.—
Bilge Ebiri,
Vulture,
7 Mar. 2025
Adjective
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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
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Since then, Putin has sought instead to rally the public to the defense of a motherland besieged by the perfidious and cunning West.—
Leon Aron,
The Atlantic,
5 Dec. 2024
Adjective
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In housing, there are numerous examples of how incorrect data has led to adverse decisions affecting people’s lives.—
State Sen. James Maroney,
Hartford Courant,
9 Mar. 2025
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But parents and activists say the numbers are incorrect since the campus consists of newer buildings, constructed decades after the school opened, and older buildings from 1957 that are used for storage, not instruction.—
Amanda Rosa,
Miami Herald,
6 Mar. 2025
Adjective
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The question of the night is the choice between selling out their souls to the vapid American tourists at the Tropicana nightclub (bad) or singing for their own people on the wrong side of the tracks (good).—
Chris Jones,
New York Daily News,
20 Mar. 2025
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But Nicol isn’t wrong to think that the real entertainment is coming from inside the house, where the spry Gita may love nothing more than to be on camera.—
Stephen Saito,
Variety,
19 Mar. 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 23 Mar. 2025.
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