Coupon
Part of speech: noun
Definition: 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. Any interest payment made or due on a bond, debenture or similar (no longer by a physical 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.
Voucher
Part of speech: noun
Definition: A piece of paper that entitles the holder to a discount, or that can be exchanged for goods and services.A receipt.A person who vouches.
Part of speech: verb
Definition: To establish the authenticity of; to vouch for.To provide a vouch for (an expenditure).To provide (a beneficiary) with a voucher.