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’
    • ‘This trade recession will be just as insidious in its effects as any market blowout.’
    • ‘The most insidious marketing comes from the baby food companies.’
    • ‘Slow calibration drift is a subtle and insidious source of unreliable instrument readings.’
    • ‘But what makes this disease insidious is that in most cases it goes undetected until it's too late.’
    • ‘The current ubiquity of advertising is certainly one of its most subtle and insidious properties.’
    • ‘Significantly, even continuous low-level noise can be an insidious stressor.’
    • ‘The more insidious problem that will remain is stacking the ballot paper in a deliberate attempt to increase the informal vote.’
    • ‘The propaganda is so insidious in the Murdoch press you can't even distinguish between news and opinion.’
    • ‘Silently and stealthily this insidious, progressive disease has taken over.’
    • ‘Their approach tends to be more subtle - and perhaps even more insidious.’
    • ‘The onset is more insidious in brain tumors and the progress to vomiting is gradual.’
    • ‘The obstruction and harassment is subtle but insidious and seriously affects the ability of the aid agencies to do their job.’
    • ‘Yet the incursions on free speech can be insidious and imperceptible.’
    • ‘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.’
    • ‘Dyens eventually left France, feeling overwhelmed by what he saw as insidious, unspoken racism.’
    • ‘There was the slow, insidious change from fresh-faced beauty to freak.’
    • ‘Increases in childhood obesity and insidious health problems are, we suspect, linked to an increased consumption of junk food.’
    • ‘An offshoot of ventriloquist journalism, these are one of the more insidious forms of misinformation.’
    • ‘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.’
    • ‘It need by no means be obvious: it can be insidious and subtle.’
    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’
      • ‘The more insidious the plot, the more difficult the cover up, and as the internet grows, so do the unanswered questions.’
      • ‘What they do is insidious, evil, and downright mean to their addict-victims like my wife.’
      • ‘I'd far rather go down in a face-to-face challenge, not after some insidious little campaign of back-biting.’
      • ‘Even the insidious cane toad can't try and sneak through quarantine.’
      • ‘They are, in my view, the most insidious of traitors.’
      • ‘I learned that you have charged that your company is the victim of an insidious conspiracy masterminded by IBM.’
      • ‘Carol Kane plays the insidious Madame Morrible as the evil twin of Mrs. Slocum from Are You Being Served?’
      • ‘His fast-talking portrayal of an insidious, damaged sexual predator is undoubtedly brilliant.’
      • ‘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.’
      • ‘Take up whatever insidious sport your smarmy boss has deemed ‘flavour of the month’.’
      • ‘Personally, we can't stand this insidious practise of sneaking adverts into non-commercial formats.’
      • ‘It harbours insidious designs in spite of its declared support for current Palestinian peace efforts.’
      • ‘The humanitarian argument is a particularly insidious one.’

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/