insidious

Definitions

in- (in) + sid (sit) + -ious = 'sitting in wait' — the posture of an ambush (Latin insidiae = an ambush). Insidious harm crouches quietly and only reveals itself when it's too late: an insidious disease creeps up unnoticed.

Why It Means This

The dread in insidious is built into its root. Latin insidiae meant 'an ambush' — soldiers in- (sitting) in wait. So an insidious threat is not loud or obvious; it lies in wait, doing quiet damage, and shows its hand only once the harm is done.

Common Collocations

• 1.insidious disease隐伏的疾病
• 2.insidious plot阴险的阴谋
• 3.[insidious] influence[暗示的]影响

Example Sentences

• 1.

  High blood pressure is an insidious condition with few early symptoms.

• 2.

  Misinformation spreads in insidious, hard-to-trace ways.