vouch·er 
/ˈvaʊtʃɚ/ noun
plural vouch·ers /ˈvaʊtʃɚ/ noun [count] : a document that gives you the right to get something (such as a product or service) without paying for it
▪ That item is out of stock, but we'll give you a voucher for 10 percent off any other item in the store. ▪ a travel voucher
▪ That item is out of stock, but we'll give you a voucher for 10 percent off any other item in the store. ▪ a travel voucher
