Definition of insidious in English:

insidious

adjective

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

    ‘sexual harassment is a serious and insidious problem’
    • ‘Silently and stealthily this insidious, progressive disease has taken over.’
    • ‘The current ubiquity of advertising is certainly one of its most subtle and insidious properties.’
    • ‘This trade recession will be just as insidious in its effects as any market blowout.’
    • ‘There was the slow, insidious change from fresh-faced beauty to freak.’
    • ‘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.’
    • ‘The onset is more insidious in brain tumors and the progress to vomiting is gradual.’
    • ‘The more insidious problem that will remain is stacking the ballot paper in a deliberate attempt to increase the informal vote.’
    • ‘The most insidious marketing comes from the baby food companies.’
    • ‘Dyens eventually left France, feeling overwhelmed by what he saw as insidious, unspoken racism.’
    • ‘The obstruction and harassment is subtle but insidious and seriously affects the ability of the aid agencies to do their job.’
    • ‘But what makes this disease insidious is that in most cases it goes undetected until it's too late.’
    • ‘Yet the incursions on free speech can be insidious and imperceptible.’
    • ‘An offshoot of ventriloquist journalism, these are one of the more insidious forms of misinformation.’
    • ‘Their approach tends to be more subtle - and perhaps even more insidious.’
    • ‘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.’
    • ‘Slow calibration drift is a subtle and insidious source of unreliable instrument readings.’
    • ‘Significantly, even continuous low-level noise can be an insidious stressor.’
    • ‘The propaganda is so insidious in the Murdoch press you can't even distinguish between news and opinion.’
    • ‘Increases in childhood obesity and insidious health problems are, we suspect, linked to an increased consumption of junk food.’
    stealthy, subtle, surreptitious, sneaking, cunning, crafty, machiavellian, artful, guileful, sly, wily, tricky, slick, deceitful, deceptive, dishonest, underhand, backhanded, indirect
    View synonyms

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

/ɪnˈsɪdɪəs/