What is Bill Obligatory?

Legal Definition
An instrument in common use and too well known to be misunderstood. It is a bond without condition, sometimes called a single bill, and differs in nothing from a promissory note, but the seal which is affixed to it. 2 Serg. & Rawle, 115. See Read's Pleaders' Assistant, 256, for a declaration setting forth such a bill. Also West's Symboleography, s. 100, 101, for the forms both with and without a penalty.
-- Bouviers Law Dictionary
Legal Definition
A bond absolute for the payment of money. It is called also a "single bill," and differs from a promissory note only in having a seal. Bank v. Greiner, 2 Serg. & R. (Pat) 115.
-- Black's Law Dictionary
Legal Definition
A promissory note under seal. See 2 Serg. & R. (Pa.) 114.
-- Ballentine's Law Dictionary