Douglas Harper's Etymology Dictionary
over-confidence
c.1700, from over- + confidence.
Usage examples of "over-confidence".
I am dealing leniently with you, Egbert, because it is a trick of the adversary to tempt to despair as well as to over-confidence.
Their enemies hadn't done that much damage to them in five millennia, and the fact that their own over-confidence had made it possible only made it worse.