Outside of the traditional, rather obvious laymen definition - Discount also applies to bond pricing, where a bond price is less than the par value. The discount is the difference between the price paid for the bond and the bond's listed price.

Example: If the par value of a bond is $1000 and the bond is currently bid at 950 - it is currency selling at a discount.

This condition will occur when the bond is high risk or offers a coupon rate well below prime.