insidious Meaning, Definition & Usage

  1. adjective satellite beguiling but harmful
    • insidious pleasures
  2. adjective satellite intended to entrap
  3. adjective satellite working or spreading in a hidden and usually injurious way
    subtle; pernicious.
    • glaucoma is an insidious disease
    • a subtle poison

WordNet

In*sid"i*ous adjective
Etymology
L. insidiosus, fr. insidiae an ambush, fr. insidere to sit in; pref. in- + sedere to sit: cf. F. insidieux. See Sit.
Definitions
  1. Lying in wait; watching an opportunity to insnare or entrap; deceitful; sly; treacherous; -- said of persons; as, the insidious foe. "The insidious witch." Cowper.
  2. Intended to entrap; characterized by treachery and deceit; as, insidious arts.
    The insidious whisper of the bad angel. Hawthorne.
    Syn. -- Crafty; wily; artful; sly; designing; guileful; circumventive; treacherous; deceitful; deceptive. -- In*sid"i*ous*ly, adv. -- In*sid"i*ous*ness, n.

Webster 1913