coupon
/ˈkuːˌpɑːn/ /ˈkjuːˌpɑːn/
noun
plural -pons
[count] a usually small piece of printed paper that lets you get a service or product for free or at a lower price
chiefly Brit :a section of an advertisement that you can cut out and mail to a company in order to request information or to order a product or service