Advertisement

insidious (adj.)

1540s, from French insidieux "insidious" (15c.) or directly from Latin insidiosus "deceitful, cunning, artful, treacherous," from insidiae (plural) "plot, snare, ambush," from insidere "sit on, occupy," from in- "in" (from PIE root *en "in") + sedere "to sit," from PIE root *sed- (1) "to sit." Figurative, usually with a suggestion of lying in wait and the intent to entrap. Related: Insidiously; insidiousness.

Others are reading

Advertisement
Advertisement
Definitions of insidious

insidious (adj.)
beguiling but harmful;
insidious pleasures
insidious (adj.)
intended to entrap;
insidious (adj.)
working or spreading in a hidden and usually injurious way;
glaucoma is an insidious disease
Synonyms: pernicious / subtle
From wordnet.princeton.edu