Adjective: insidious in'si-dee-us
- Working or spreading in a hidden and usually injurious way
"glaucoma is an insidious disease";
- pernicious, subtle
- Beguiling but harmful
"insidious pleasures"
- Intended to entrap
"The insidious plot was designed to lure unsuspecting victims"
See also: dangerous, harmful, seductive, unsafe
Encyclopedia: Insidious