- 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.
Origin of insidious
Synonyms for insidiousSee more synonyms for on Thesaurus.com
Related Words for insidiousnessinfidelity, falsehood, fraud, trickery, duplicity, chicanery, deceit, mendacity, treachery, corruption, graft, criminality, infamy, falsity, stealing, shadiness, artifice, racket, double-dealing, cheating
Examples from the Web for insidiousness
Historical Examples of insidiousness
We suspected not that deceit, insidiousness, and slavery were to be found beneath the sun.Imogen
Its insidiousness makes it exceedingly difficult to recognize.Outlines of dairy bacteriology
H. L. Russell
As to his character: it is too bad to associate him with so much craft and insidiousness.Christmas Penny Readings
George Manville Fenn
They believed in the personality, activity and insidiousness of the Devil.Unfettered
Sutton E. Griggs
The insidiousness of its design has been equalled only by the shameless manner of its being carried into execution.The Life of John Marshall (Volume 2 of 4)
Albert J. Beveridge
- stealthy, subtle, cunning, or treacherous
- working in a subtle or apparently innocuous way, but nevertheless deadlyan insidious illness
Word Origin for insidious
- Being a disease that progresses with few or no symptoms to indicate its gravity.