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
But most of its failures are subtler, more insidious.
—
Katy Waldman,
New Yorker,
10 June 2026
What makes this deal particularly insidious is the trade-off at its core.
—
Joe Wilkins,
Futurism,
10 June 2026
But there is an insidious quality.
—
Rory McDonald,
Fortune,
6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—
Keith Langston,
PEOPLE,
6 June 2026
See All Example Sentences for insidious
Katy Waldman,
New Yorker,
10 June 2026
What makes this deal particularly insidious is the trade-off at its core.
—
Joe Wilkins,
Futurism,
10 June 2026
But there is an insidious quality.
—
Rory McDonald,
Fortune,
6 June 2026
Best known for comedy series like Community (2009-15) and GLOW (2017-19), Alison Brie is taking on the role of Evil-Lyn, an insidious enchantress who serves as Skeletor’s main accomplice.
—
Keith Langston,
PEOPLE,
6 June 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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The infamous cyclops briefly appeared, as well as footage of Odysseus and his men battling the cannibalistic race of giants known as Laestrygonians and navigating around the treacherous whirlpool Charybdis.
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According to the hiking blog, The Hiking HI, the rock bridge can only be traversed at low tide, but can be treacherous either way.
Adjective
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Obviously there’s a resemblance but in a really subtle and tasteful way.
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Your reward will be the sight of a tiny pale point with a subtle blue-green tint.
Adjective
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The charge alleges a person knowingly defrauded another by using false or misleading information to obtain money, property, credit or a loan.
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Opponents of Amendment 5 have flatly called the advertisement misleading or false.
Adjective
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Shadow fleet vessels disguise their identity and purpose through a broad range of deceptive activities, including spoofing their locations and destinations.
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The complaint alleged deceptive advertising and other misconduct.
Adjective
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This is perhaps the most perfidious practice of this sort of politics.
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The government took a genuine invitation to collaborate as a perfidious power grab.
Adjective
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Released Parties are also not responsible for any incorrect or inaccurate information, whether caused by site users, tampering, hacking, or by any equipment or programming associated with or utilized in the Giveaway.
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At the same time, The New York Times reported that Google’s AI Overviews produced incorrect answers roughly one in 10 times.
Adjective
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Critics, and even some supporters, said Soto-Martínez was making his move at the wrong time.
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That could always be wrong, of course, but at least that’s the garage talk heading into the weekend.
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 7 Jul. 2026.
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