insidious
Pronunciation:
/ɪnˈsɪdi.əs/adjective
Definitions
Producing harm in a stealthy, often gradual, manner.
Intending to entrap; alluring but harmful.
Example: Hansel and Gretel were lured by the witch’s insidious gingerbread house.
Treacherous.
Example: The battle was lost due to the actions of insidious defectors.