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
That is exactly what this film cleverly does — pinpoints the insidious nature of far-right movements and the creeping rhetoric that has polluted our society.
—
Alex Ritman, Variety, 30 Apr. 2026
The accumulation of heavy metals is insidious.
—Anton L. Delgado, Los Angeles Times, 29 Apr. 2026
It's aptly named after LV-426, the infamous planetoid that the interstellar towing vessel USCSS Nostromo set down upon to discover the derelict spaceship and its insidious contents in the classic 1979 feature film.
—Jeff Spry, Space.com, 27 Apr. 2026
Hillsides covered in fuel The hills surrounding Concepción, Penco and Lirquén appear deep green from the air, carpeted in trees, and in the thickness of these forests lies an insidious risk.
—Stefano Pozzebon, CNN Money, 26 Apr. 2026
See All Example Sentences for insidious
Alex Ritman, Variety, 30 Apr. 2026
The accumulation of heavy metals is insidious.
—Anton L. Delgado, Los Angeles Times, 29 Apr. 2026
It's aptly named after LV-426, the infamous planetoid that the interstellar towing vessel USCSS Nostromo set down upon to discover the derelict spaceship and its insidious contents in the classic 1979 feature film.
—Jeff Spry, Space.com, 27 Apr. 2026
Hillsides covered in fuel The hills surrounding Concepción, Penco and Lirquén appear deep green from the air, carpeted in trees, and in the thickness of these forests lies an insidious risk.
—Stefano Pozzebon, CNN Money, 26 Apr. 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
-
So for graduates walking into a treacherous student debt landscape, even a single round of loan forgiveness can help.—
Sydney Lake,
Fortune,
13 May 2026
-
Under the cover of darkness, the Traitors murder the Faithful one by one in a treacherous spree while the Faithful try to uncover the Traitors and banish them from the game.—
Nellie Andreeva,
Deadline,
11 May 2026
Adjective
-
She was left to ponder empty dresser drawers and piece together the subtle clues of their final days together.—
Miami Herald Archives,
Miami Herald,
20 May 2026
-
The photo reveals subtle imperfections in the arc of the moon's crescent, created as sunlight fell on craters and broken terrain lining the shadowy divide separating night from day on the lunar surface.—
Anthony Wood,
Space.com,
20 May 2026
Adjective
-
On May 14, Dana Williamson, a former top aide to Newsom and onetime Becerra political adviser, pleaded guilty in federal court after accepting a plea deal to multiple charges, including committing bank and wire fraud, filing a false tax return, and lying to the FBI.—
James Ward,
USA Today,
15 May 2026
-
Dana Williamson, former top aide to Newsom, pleaded guilty in an FBI corruption probe to bank fraud, filing a false tax return and lying to the FBI.—
Sacbee.com,
Sacbee.com,
15 May 2026
Adjective
-
The Request for Investigation, shared exclusively with Fortune ahead of its public filing on Wednesday, alleges that Roblox is violating Section 5 of the FTC Act through unfair and deceptive practices.—
Catherina Gioino,
Fortune,
20 May 2026
-
That fueled the storyline that Valerie would be the only person actually working on the show who knows the scripts are being written by AI, reflecting how careful, and in some cases, downright deceptive, those in Hollywood are in revealing their use of AI.—
Chris O'Falt,
IndieWire,
19 May 2026
Adjective
-
Pakistan was a perfidious ‘ally’ in Afghanistan, backing the Taliban while pretending to be our friends.—
Efrat Lachter,
FOXNews.com,
18 Apr. 2026
-
The government took a genuine invitation to collaborate as a perfidious power grab.—
Gideon Lewis-Kraus,
New Yorker,
14 Mar. 2026
Adjective
-
However, the indictment alleges the ship was using an incorrect fuel pump, which did not have redundancies.—
JT Moodee Lockman,
CBS News,
20 May 2026
-
Customer reviews frequently praise Origin’s tracking accuracy compared to competing budgeting apps, though some users report occasional issues with incorrect transaction categorization.—
Amy DeYoung,
USA Today,
20 May 2026
Adjective
-
The following seasons saw a wrong turn and regression to the point where many supporters gave up.—
Carl Anka,
New York Times,
17 May 2026
-
For most people, this is where the cocktail goes wrong.—
Jason O'Bryan,
Robb Report,
16 May 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 23 May. 2026.
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