Origin of insidious
Can be confusedinsidious invidious
Examples from the Web for insidiously
Others, more quietly but just as insidiously, operate from the Muslim religious right.
There was a muggy warmth in it which relaxed their muscles and insidiously slackened the domination of their will.Long Odds|Harold Bindloss
That is the cocher's special mission in life—subtly and insidiously to humiliate the tourist.A Wanderer in Paris|E. V. Lucas
Yet, it is insidiously objected, their craziness or their possessedness is at least their sin.The Ego and His Own|Max Stirner
Because it nailed him to environment that insidiously sapped his manhood, along with his mental and manual skill.Criminal Types|V. M. Masten
A tendency to undermine the best interests of the art is, however, insidiously at work to misguide the public taste.