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
Real-life horror of one’s own body is the most insidious kind of body horror at play here, though James’ film offers a measure of the gorily fantastical stuff too.
—
Guy Lodge, Variety, 28 Jan. 2026
This insidious development is reversing at double speed the process of self-reinforcement—the hiring of original and distinctive talent and the building of reputations for competence and probity—that brings institutions their authority.
—Sean Williams, Harpers Magazine, 27 Jan. 2026
As the death count rises from the state’s violent response to peaceful protests, the Islamic Republic’s internet blackout has proved more insidious.
—Nahid Siamdoust, The Atlantic, 23 Jan. 2026
Daniel Kaluuya stars as a Black photographer visiting his white girlfriend's parents and is terrified to discover the truly insidious reason for his invitation.
—Brian Truitt, USA Today, 22 Jan. 2026
See All Example Sentences for insidious
Guy Lodge, Variety, 28 Jan. 2026
This insidious development is reversing at double speed the process of self-reinforcement—the hiring of original and distinctive talent and the building of reputations for competence and probity—that brings institutions their authority.
—Sean Williams, Harpers Magazine, 27 Jan. 2026
As the death count rises from the state’s violent response to peaceful protests, the Islamic Republic’s internet blackout has proved more insidious.
—Nahid Siamdoust, The Atlantic, 23 Jan. 2026
Daniel Kaluuya stars as a Black photographer visiting his white girlfriend's parents and is terrified to discover the truly insidious reason for his invitation.
—Brian Truitt, USA Today, 22 Jan. 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
-
Moltzan’s run was especially impressive given the treacherous nature of the slalom course on Tuesday, as eight of the 26 racers either did not finish or were disqualified.—
Molly Hunter,
NBC news,
10 Feb. 2026
-
Farley saw firsthand how a Bronco helped a Utah search and rescue team navigate treacherous terrain during real rescue missions, Cope said.—
Jamie L. LaReau,
USA Today,
8 Feb. 2026
Adjective
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The moments that could be regarded as direct criticism were rare and subtle.—
Orlando Sentinel Editorial Board,
The Orlando Sentinel,
11 Feb. 2026
-
The skirt is made with an intentionally creased texture and features a straight cut with a subtle flare at the hem.—
Karla Rodriguez,
Footwear News,
11 Feb. 2026
Adjective
-
Authorities did not provide additional details about the agents' apparently false statements.—
Nicole Acevedo,
NBC news,
13 Feb. 2026
-
Nevertheless, Worden continued to promote the false claim to news outlets and hired a media consultant to amplify it, the documents said.—
Marc Ramirez,
USA Today,
13 Feb. 2026
Adjective
-
Savings are only on brand names, which can be deceptive when comparing prices.—
Tom Gavin,
EverydayHealth.com,
10 Feb. 2026
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Novo has so far filed around 130 lawsuits dealing with deceptive marketing practices and consumer fraud, Kuckelman said.—
Annika Kim Constantino,
CNBC,
9 Feb. 2026
Adjective
-
Observing human behavior confirms that for some among us, the perfidious lust for unbridled power and the imposition of cruelty in its quest know no bounds and are bereft of human decency.—
A.O. Scott,
New York Times,
3 Feb. 2026
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However, this question has now been resurrected and amplified by conservatives as evidence of a perfidious lack of patriotism.—
Charlie Campbell,
Time,
2 Feb. 2026
Adjective
-
Some will always believe their placement incorrect.—
Eric Sondheimer,
Los Angeles Times,
10 Feb. 2026
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Both parties claim problems such as invalid signatures and missing or incorrect voter information on petitions that judicial candidates submit to secure a place on the ballot.—
Kamal Morgan,
Fort Worth Star-Telegram,
10 Feb. 2026
Adjective
-
Nichols and Vann concede that handing the cup with the apple juice and urine mix to Smith’s son to drink was wrong and Vann has expressed regret for that.—
Jane Harper,
Dallas Morning News,
7 Feb. 2026
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The crash involved a wrong-way driver on eastbound I-84, according to an Idaho State Police Facebook post.—
Shannon Tyler,
Idaho Statesman,
7 Feb. 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 15 Feb. 2026.
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