\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.