intended to entrap or beguile: an insidious plan.
stealthily treacherous or deceitful: an insidious enemy.
operating or proceeding in an inconspicuous or seemingly harmless way but actually with grave effect: an insidious disease.
- in·sid·i·ous·ly, adverb
- in·sid·i·ous·ness, noun
- un·in·sid·i·ous, adjective
- un·in·sid·i·ous·ly, adverb
- un·in·sid·i·ous·ness, noun
- insidious , invidious
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use insidious in a sentence
Though they’re inaudible to human ears, whose range bottoms out at 20 Hz, the interval creates some fairly insidious side effects.
Ginsburg delivered her dissent aloud from the bench, accusing her colleagues of either ignoring or failing to comprehend the “insidious” nature of pay discrimination, and called on Congress to act.How A Conservative 6-3 Majority Would Reshape The Supreme Court | Amelia Thomson-DeVeaux (Amelia.Thomson-DeVeaux@abc.com) | September 28, 2020 | FiveThirtyEight
The most insidious problem, however, is the varroa mite, appropriately named Varroa destructor.The Fungal Evangelist Who Would Save the Bees - Issue 90: Something Green | Merlin Sheldrake | September 23, 2020 | Nautilus
Indeed, air conditioning represents one of the most insidious challenges of climate change, and one of the most difficult technological problems to fix.Air conditioning technology is the great missed opportunity in the fight against climate change | James Temple | September 1, 2020 | MIT Technology Review
Such a situation is particularly insidious because the pay gap she experiences would often go undetected.
Is it anti-Semitism, or are less insidious cultural forces at work?Why Was Bess Myerson the First and Last Jewish Miss America? | Emily Shire | January 7, 2015 | THE DAILY BEAST
But its far more insidious role was revealed, whether it was gun policies or voter suppression.
The act of erasure through mis- or under-representation is an insidious one.
Its insidious reach enters into medical offices and chokes off the free-speech rights of the people trying to work there.
But the commentary that McCarthy gets from her so-called supporters is often just as cruel, but somehow more insidious.The Trials of ‘Tammy’: Stop Policing Melissa McCarthy’s Body | Teo Bugbee | July 7, 2014 | THE DAILY BEAST
Play-writing is a luxury to a journalist, as insidious as golf and much more expensive in time and money.First Plays | A. A. Milne
Each cachet contained three decigrams of malourea, the insidious drug notorious under its trade name of Veronal.Dope | Sax Rohmer
The state of affairs which has come about was uncertain in origin, insidious in growth, and has developed over a wide field.Report of the Special Committee on Moral Delinquency in Children and Adolescents | Oswald Chettle Mazengarb et al.
She believed he sought her, and she must needs fight an insidious liking for him.Repertory Of The Comedie Humaine, Complete, A -- Z | Anatole Cerfberr and Jules Franois Christophe
This is a thing I would despise in anybody else; but he is so jolly insidious 240 and ingratiating!The Works of Robert Louis Stevenson - Swanston Edition Vol. 25 (of 25) | Robert Louis Stevenson
British Dictionary definitions for insidious
stealthy, subtle, cunning, or treacherous
working in a subtle or apparently innocuous way, but nevertheless deadly: an insidious illness
- insidiously, adverb
- insidiousness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012