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1. Working or spreading harmfully in a subtle or stealthy manner: insidious rumors; an insidious disease.
2. Intended to entrap; treacherous: insidious misinformation.
3. Beguiling but harmful; alluring: insidious pleasures.

[From Latin īnsidiōsus, from īnsidiae, ambush, from īnsidēre, to sit upon, lie in wait for : in-, in, on; see in-2 + sedēre, to sit; see sed- in Indo-European roots.]

in·sid′i·ous·ly adv.
in·sid′i·ous·ness n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.insidiousness - subtle and cumulative harmfulness (especially of a disease)
harmfulness, injuriousness - destructiveness that causes harm or injury
2.insidiousness - the quality of being designed to entrap
perfidiousness, perfidy, treachery - betrayal of a trust
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
And through their stories, we find the insidiousness of the prevailing structures and systems that cultivate hate, injustice and oppression.
conflict or struggle, or the threat of disruption." (19) This is the brilliance and the insidiousness of Spencer's position.
Should we talk about insidiousness? The average attack package takes less than 48 hours to take control of a network and will remain there for 146 days before detection.
The CDC maintains updates on the diagnosis, treatment, and environmental decontamination procedures for Candida auris at and continues to update the site due to the insidiousness and potentially deadliness of this emerging mycotic infection.
Depp dials down the pantomime villainy, opting for slow-burning insidiousness that unsettles rather than flatly chills.
Our society would be well-served by sinking the sickening psychobabble plopped upon the populace under the guise that implicit bias claims would bring about "progress." It follows the royal crown roll out of the Rock 'Em Sock 'Em "Diversity and Inclusion" insidiousness that was so overplayed it is now akin to feeble Weebles wobbling, but they won't fall down off the back ends of websites only for fear of the politically incorrect label by long-view liberals in our era of selective alt-sensitivity.
The insidiousness of taking offense is in this: when we call out people not to educate them but out of spite, anger and rage.
Assimilation here highlights the insidiousness of colonial power.
The Milan's court acquittal of Luca Volonte, the former chair of the European People's Party group in PACE, who was accused of corruption ties with Azerbaijan, once again exposed the lies and insidiousness of Armenians and pro-Armenian forces, Azerbaijani MP Elman Nasirov told Trend on Feb.14.
In addition to providing a necessary foundation, these early chapters bring into stark focus the severity and insidiousness of the problem with the use of examples that shatter common misconceptions about who are the purveyors and victims of online abuse.