Definition of insidious in English:

insidious

adjective

  • 1Proceeding in a gradual, subtle way, but with harmful effects.

    ‘sexually transmitted diseases can be insidious and sometimes without symptoms’
    • ‘The current ubiquity of advertising is certainly one of its most subtle and insidious properties.’
    • ‘The more insidious problem that will remain is stacking the ballot paper in a deliberate attempt to increase the informal vote.’
    • ‘It need by no means be obvious: it can be insidious and subtle.’
    • ‘Slow calibration drift is a subtle and insidious source of unreliable instrument readings.’
    • ‘There was the slow, insidious change from fresh-faced beauty to freak.’
    • ‘Yet the incursions on free speech can be insidious and imperceptible.’
    • ‘The onset is more insidious in brain tumors and the progress to vomiting is gradual.’
    • ‘Significantly, even continuous low-level noise can be an insidious stressor.’
    • ‘The obstruction and harassment is subtle but insidious and seriously affects the ability of the aid agencies to do their job.’
    • ‘Silently and stealthily this insidious, progressive disease has taken over.’
    • ‘Their approach tends to be more subtle - and perhaps even more insidious.’
    • ‘An offshoot of ventriloquist journalism, these are one of the more insidious forms of misinformation.’
    • ‘The most insidious marketing comes from the baby food companies.’
    • ‘Dyens eventually left France, feeling overwhelmed by what he saw as insidious, unspoken racism.’
    • ‘Nuclear disc lesions are of gradual or insidious onset, the history may be on and off back pain for weeks and back pain getting worse.’
    • ‘This trade recession will be just as insidious in its effects as any market blowout.’
    • ‘Increases in childhood obesity and insidious health problems are, we suspect, linked to an increased consumption of junk food.’
    • ‘The propaganda is so insidious in the Murdoch press you can't even distinguish between news and opinion.’
    • ‘But what makes this disease insidious is that in most cases it goes undetected until it's too late.’
    • ‘Our sport is rife with that same insidious elitism that has decayed the core of other field sports, which now face the very real prospect of being outlawed.’
    stealthy, subtle, surreptitious, sneaking, cunning, crafty, machiavellian, artful, guileful, sly, wily, tricky, slick, deceitful, deceptive, dishonest, underhand, backhanded, indirect
    View synonyms
    1. 1.1 Treacherous; crafty.
      ‘tangible proof of an insidious alliance’
      • ‘Personally, we can't stand this insidious practise of sneaking adverts into non-commercial formats.’
      • ‘They are, in my view, the most insidious of traitors.’
      • ‘His fast-talking portrayal of an insidious, damaged sexual predator is undoubtedly brilliant.’
      • ‘I'd far rather go down in a face-to-face challenge, not after some insidious little campaign of back-biting.’
      • ‘Carol Kane plays the insidious Madame Morrible as the evil twin of Mrs. Slocum from Are You Being Served?’
      • ‘Even the insidious cane toad can't try and sneak through quarantine.’
      • ‘Take up whatever insidious sport your smarmy boss has deemed ‘flavour of the month’.’
      • ‘What they do is insidious, evil, and downright mean to their addict-victims like my wife.’
      • ‘The humanitarian argument is a particularly insidious one.’
      • ‘And yet, the same argument reinvents itself time and again in all sorts of insidious avatars.’
      • ‘But there's nothing laughable about the creature itself, a thoroughly insidious and hateful little beast.’
      • ‘It harbours insidious designs in spite of its declared support for current Palestinian peace efforts.’
      • ‘I learned that you have charged that your company is the victim of an insidious conspiracy masterminded by IBM.’
      • ‘The more insidious the plot, the more difficult the cover up, and as the internet grows, so do the unanswered questions.’

Origin

Mid 16th century: from Latin insidiosus ‘cunning’, from insidiae ‘an ambush or trick’, from insidere ‘lie in wait for’, from in- ‘on’ + sedere ‘sit’.

Pronunciation

insidious

/inˈsidēəs//ɪnˈsɪdiəs/