1) A sum owed by one person or organization to another. In commerce, it is usual for debts to be required to be settled within one month of receiving an invoice, after which interest may be incurred. A long-term debt may be covered by a bill of exchange, which can be a negotiable instrument.
See also: debenture
2) Any funding instrument other than equity, such as a bond or a promissory note.

Accounting dictionary. 2014.