voucher

noun

1. A piece of paper or other token that entitles the holder to a discount, or that can be exchanged for goods and services.

   “a voucher for a free kettle”

   “This voucher entitles the bearer to a 20% discount on frozen goods.”

   “Today, clients who cannot afford the reasonable rates are able to join a work-voucher system in which they agree to work for an hour helping the HCHS staff for each hour of service received.”

2. A receipt.
3. One who or that which vouches.

   “To the fashionable world he cannot be a stranger […] and his having married a sister of the Duke of Leeds is a voucher for my assertion.”

   “She is my sister—my own father’s daughter. Well; why do I believe it? The other day I had not so much as heard the remotest rumor of her existence; and what has since occurred to change me? What so new and incontestable vouchers have I handled? None at all.”

4. A copy of a published advertisement sent by the agency to the client as proof of publication.

   “Most agencies also have a vouchers department. It is its responsibility to obtain a copy of every advertisement that appears in print. It supplies the accounts department with the relevant newspaper or magazine, which is affixed to the agency's invoice for the space.”

5. (historical)A mechanical device used in shops for automatically registering the amount of money drawn.

verb

1. (transitive)To establish the authenticity of; to vouch for.
2. (transitive)To provide a vouch for (an expenditure).
3. (transitive)To provide (a beneficiary) with a voucher.