What does the word insidious mean?

Usage examples for insidious

  1. He tried in many insidious ways to stimulate the boys to think out and carry forward original work, and in almost every instance he succeeded in doing this in such a way that the boys themselves suggested the work to be done. – The Wonder Island Boys: Exploring the Island by Roger Thompson Finlay
  2. I never dreamed of jealousy, Alfred Bernard, or I might have seen beforehand the wiles of the insidious tempter. – Hansford: A Tale of Bacon's Rebellion by St. George Tucker
  3. Phil Abingdon had experienced in her own person the insidious power of Ormuz Khan. – Fire-Tongue by Sax Rohmer