ETYMOLOGY
from un- + heedy (heedful, careful, cautious)
EXAMPLE
“… Vpon vvhom he is sayd so much to haue doted, that in regard of her excellencie, he scorned & wrote against the beauty of Helena. For which his praesumptuous and vnheedie hardinesse, he is sayde by vengeaunce of the Gods, thereat being offended, to haue lost both his eyes. …”
From: The Shepheardes Calender conteyning tvvelue æglogues proportionable to the twelue monethes
By Edmund Spenser, 1579
Lexicophilia 