Origin: French suffix -age
Overage has 5 different meanings across 2 categories:
a surplus or excess of money or merchandise that is actually on hand and that exceeds expectations
A surplus of inventory or capacity or of cash that is greater than the amount in the record of an account.
To have too long an aging process.
too old to be useful
"He left the house...for the support of twelve superannuated wool carders"
Having an age that is greater than a stipulated minimum.