overweening \oh-vur-WEE-ning\, adjective:
1. Overbearing; arrogant; presumptuous.
2. Excessive; immoderate; exaggerated.
Overweening is from Middle English overwening, present participle of overwenen, "to be arrogant," from over + wenen "to ween," from Old English wenan.
In a story as old as the Greeks, overweening pride brought condign disaster.
-- David Frum, How We Got Here