Insidious
/ɪnˈsɪdiəs/adjective
Something or someone that slowly and secretly causes harm.
He had a heart condition that was insidious because its damage was silent and not immediate.
Often appears as...
- insidious disease
- insidious problem
Definition 1 of 2
Pro Tip 1/3Hidden Harm
Use 'insidious' for problems that worsen without obvious symptoms.
The spy's insidious sabotage went unnoticed until it was too late.
Pro Tip 2/3Slow Progression
Describes something harmful developing gradually, which may be difficult to detect initially.
Climate change is an insidious threat that evolves over decades.
Pro Tip 3/3Cultural Nuance
'Insidious' is often used to describe sly tactics or conspiracies in movies and literature.
The insidious plot of the villain in the novel kept readers on edge.
Compare with
cunningdeceitfuldeviousduplicitoussneakysubtletreacheroustricky
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