1 beguiling but harmful; "insidious pleasures"
2 intended to entrap
3 working or spreading in a hidden and usually injurious way; "glaucoma is an insidious disease"; "a subtle poison" [syn: pernicious, subtle]
- Webster 1913
Byzantine, Machiavellian, Machiavellic, acute, amoral, arch, artful, astute, cagey, calculating, canny, chiseling, clever, collusive, conscienceless, corrupt, corrupted, covinous, crafty, criminal, crooked, cunning, cute, dangerous, dark, deceitful, deep, deep-laid, designing, devious, diplomatic, dishonest, dishonorable, doubtful, dubious, evasive, false, falsehearted, feline, felonious, finagling, fishy, foxy, fraudulent, furtive, gradual, guileful, ill-got, ill-gotten, immoral, indirect, ingenious, inventive, knowing, not kosher, pawky, perfidious, perilous, politic, questionable, ready, resourceful, rotten, scheming, serpentine, shady, shameless, sharp, shifty, shrewd, sinister, slick, slippery, sly, smooth, snaky, sneaky, sophistical, stealthy, strategic, subtile, subtle, supple, surreptitious, suspicious, tactical, treacherous, trickish, tricksy, tricky, two-faced, unconscienced, unconscientious, unconscionable, underhand, underhanded, unethical, unprincipled, unsavory, unscrupulous, unstraightforward, vulpine, wary, wily, without remorse, without shame