Promissory

Prom"is*so*ry (?), a. Containing a promise or binding declaration of something to be done or forborne.

Promissory note (Law), a written promise to pay to some person named, and at a time specified therein, or on demand, or at sight, a certain sum of money, absolutely and at all events; -- frequently called a note of hand. Kent. Byles. Story.