Dictionary

insidious en · ADJ

Pronunciation

• /ɪnˈsɪdi.əs/
• (US) audio

Etymology

From Middle French insidieux, from Latin īnsidiōsus (“cunning, artful, deceitful”), from īnsidiae (“a lying in wait, an ambush, artifice, stratagem”) + -ōsus, from īnsideō (“to sit in or on”), from in (“in, on”) + sedeō (“to sit”).

Meanings

1. Causing harm in a stealthy, often gradual, manner.
   • At some point in time they may become the source of an insidious cancer. 1997, Matthew Wood, The book of herbal wisdom: using plants as medicine:
   • The impact on rural communities of rail closures was acute, but I would argue that the worst outcome it created was the long-term diminishment of suburban capacity outside London, which has had a far more insidious effect on rail usage nationally. 2023 March 8, Gareth Dennis, “The Reshaping of things to come...”, in RAIL, number 978, page 49:
   • The nurse always must be alert to signs of slow leak or insidious infiltration. 2007, Sharon Weinstein, Ada Lawrence Plumer, Principles and practice of intravenous therapy:
   • Strong and vigorous man as he looks, Livingstone has been for years the victim of a secret and insidious disease. 1847, George Lippard, The Quaker City: or, The monks of Monk-Hall:
2. Intending to entrap; alluring but harmful.
   • The insidious whispers of the bad angel. 1850, Nathaniel Hawthorne, chapter 5, in The Scarlet Letter, a Romance, Boston, Mass.: Ticknor, Reed, and Fields, →OCLC:
   • All these facts clearly appear to me now to establish that the sanctioned scheme was a part of a bigger and […] more insidious scheme which was to hoodwink the creditors and to firmly establish and consolidate the position […] 1948, D.V. Chitaley (editor or publisher), All India Reporter, volume 3, page 341
   • Hansel and Gretel were lured by the witch’s insidious gingerbread house.
   • This seemed to her the worst defilement into which this insidious city had cheated her and in her agitation, she nearly ran into the latrine, […] 2005, Anita Desai, Voices in the City, page 189
   • Gashford slid his cold insidious palm into his master's grasp, and so, hand in hand, and followed still by Barnaby and by his mother too, they mingled with the concourse. 1841 February–November, Charles Dickens, “Barnaby Rudge. Chapter 48.”, in Master Humphrey’s Clock, volume III, London: Chapman & Hall, […], →OCLC, page 215:
   • This is the insidious way sports entrap you: you follow a player, which commits you to his team. You begin to acquire scraps of utterly useless information about teammates, managers, owners, trainers, agents, lawyers. 2007, Joseph Epstein, Narcissus Leaves the Pool, page 171:
   • They all sought the President's views on the world situation in general and the Asian situation in particular. Without mincing words he would comment on his favorite theme, namely, the insidious scheme of the international Communists to conquer the free world. 1983, James C. H. Shen, “Rejoining the Government”, in Robert Myers, editor, The U.S. & Free China: How the U.S. Sold Out Its Ally, Washington, D.C.: Acropolis Books Ltd., →ISBN, →LCCN, →OCLC, page 28:
   • The atmosphere of this insidious city comes out to meet him the moment he touches the European shore; for in London he meets Maria Gostrey just over from France. 1969, Dorothy Brewster, John Angus Burrell, Dead reckonings in fiction:
3. (nonstandard) Treacherous.
   • ‘Believe me,’ he shouted, ‘these insidious folk talk dangerous nonsense. I hear they are spouting out their ridiculous platitudes not five miles from this park in which we are standing…’ 1912, Ralph Straus, The prison without a wall:
   • The battle was lost due to the actions of insidious defectors.
   • But with whom do you contract that alliance? With the natural enemy of France — that insidious house of Austria — which detests our country from feeling, system, and necessity. 1858, Phineas Camp Headley, The life of the Empress Josephine: first wife of Napoleon:

Forms

Deriveds

uninsidious · insidiously · insidiousness

Synonyms

recreant · trothless · traitorlike · dastardly · subtle · false · disleal · insidious · traitorous · traitorous · false-hearted · hollow-hearted · unsteadfast · disloyal · unloyal · unfaithful · renegade · falseheart · proditory · Punic · guileful · double-dealing · viperous · double-faced · traitorly · double-crossing · illoyal · Judasly · proditorious · reptitious · treachersome · nonfaithful · guiled · doublehearted · viperish · ratlike · traitorish · perfidious · proditorious · swike · infidelitous · traitorsome · reptilian · Judaslike · treacherous · double-hearted · faithless · untrue · booky · unleal · perfidious

Translations (48)

it insidioso (causing harm in a stealthy, often gradual, manner) · ru хи́трый (causing harm in a stealthy, often gradual, manner) · hy նենգ (causing harm in a stealthy, often gradual, manner) · de hinterhältig (intending to entrap) · bg лукав (intending to entrap) · pl podstępny (causing harm in a stealthy, often gradual, manner) · fi salakavala (intending to entrap) · bg коварен (intending to entrap) · fr insidieux (causing harm in a stealthy, often gradual, manner) · de schleichend (causing harm in a stealthy, often gradual, manner) · fi juonikas (intending to entrap) · ota آصمق (causing harm in a stealthy, often gradual, manner) · sh шкодљив (causing harm in a stealthy, often gradual, manner) · de heimtückisch (causing harm in a stealthy, often gradual, manner) · pt insidiador (intending to entrap) · sv lömsk (causing harm in a stealthy, often gradual, manner) · mk подмолен (causing harm in a stealthy, often gradual, manner) · ru кова́рный (intending to entrap) · izh salakavala (intending to entrap) · ru кова́рный (causing harm in a stealthy, often gradual, manner) · it subdolo (intending to entrap) · ca insidiós (intending to entrap) · sv försåtlig (causing harm in a stealthy, often gradual, manner) · de heimtückisch (intending to entrap) · ru скры́тый (causing harm in a stealthy, often gradual, manner) · km ដែលបញ្ឆោត (causing harm in a stealthy, often gradual, manner) · sh škodljiv (causing harm in a stealthy, often gradual, manner) · fi salakavala (causing harm in a stealthy, often gradual, manner) · mi toropuku (causing harm in a stealthy, often gradual, manner) · sv förrädisk (intending to entrap) · cmn 狡詐 /狡诈 (causing harm in a stealthy, often gradual, manner) · cmn 潛移默化的 /潜移默化的 (causing harm in a stealthy, often gradual, manner) · nl verraderlijk (causing harm in a stealthy, often gradual, manner) · da lumsk (causing harm in a stealthy, often gradual, manner) · eo insida (causing harm in a stealthy, often gradual, manner) · la insidiosus (causing harm in a stealthy, often gradual, manner) · bg коварен (causing harm in a stealthy, often gradual, manner) · es insidioso (intending to entrap) · pt insidioso (causing harm in a stealthy, often gradual, manner) · tr sinsice (causing harm in a stealthy, often gradual, manner) · nl sluipend (causing harm in a stealthy, often gradual, manner) · cmn 陰險 /阴险 (causing harm in a stealthy, often gradual, manner) · ro insidios (causing harm in a stealthy, often gradual, manner) · pl zdradliwy (causing harm in a stealthy, often gradual, manner) · cs zákeřný (causing harm in a stealthy, often gradual, manner) · de hinterlistig (intending to entrap) · es insidioso (causing harm in a stealthy, often gradual, manner) · pl zdradziecki (causing harm in a stealthy, often gradual, manner)