Bill single

A written promise to pay to a person or persons named a stated sum at a stated time, without any condition. When under seal, as is usually the case, it is sometimes called a "bili obligatory," (q. v.) It differs from a "bili penal," (g. v.,) in that it expresses no penalty. 8.

In commercial law. A written statement of the terms of a contract, or specification of the items of a transaction or of a demand; also a general name for any item of indebtedness, whether receivable or payable. -Bill-book.

In mercantile law. A book in which an account of bills of exchange and promissory notes, whether payable or receivable, is stated.
Defined under Bill in Black's Law Dictionary.

and PENAL. A written engagement under seal for the payment of money, either on demand, or at a future day, formerly in common use; the penal bill being framed with a penalty, and the single bill, (which was the more usual form), without. Cro. JSliz. 548. Whishaw. Single bills are now, however, superseded bjr the modem bills and notes, and penal bdls by bonds or obligations.