coupon

A section of a ticket, showing the holder to be entitled to some specified accommodation or service, as to a passage over a designated line of travel, a particular seat in a theater, a discount, etc.

A voucher issued by a manufacturer or retailer which offers a discount on a particular product.

(finance, obsolete) A certificate of interest due, printed at the bottom of transferable bonds (state, railroad, etc.), given for a term of years, designed to be cut off and presented for payment when the interest is due; an interest warrant.