A paper having on it these letters, with a sum named, and duly signed; -- in use in England as an acknowledgment of a debt, and taken as evidence thereof, but not amounting to a promissory note; a due bill.
I O U
Meaning of I O U in English
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012