Insidious

Adjective

 * 1) Producing harm in a stealthy, often gradual, manner.
 * 2) Intending to entrap; alluring but harmful.
 * 3) Treacherous; subtle, seductive.

Adverbs for Insidious
peculiarly; subtly; dangerously; alarmingly; appallingly; cunningly; shrewdly; terrifyingly; particularly; shockingly; ominously; uncomfortably; deceptively; surreptitiously; elusively; fraudulently; slyly; profoundly; cleverly; artfully; astutely; shabbily; wickedly; perfidiously; shamefully; trickily.

Thesaurus
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, 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,

Etymology
From insidiosus:, from insidiae: + -osus:, from insideo:, from in: + sedeo:.

Derived terms

 * insidiously
 * insidiousness

Translations

 * Dutch: sluipend
 * Finnish:
 * French: insidieux


 * Romanian: insidios
 * Russian: скрытый


 * Finnish: ,