voucher

Etymology

From vouch + -er. The verb is from the noun.

noun

1. A piece of paper that entitles the holder to a discount, or that can be exchanged for goods and services.
   This voucher can be redeemed at any Walmart in the state until March 31 2013.
   a voucher for a free kettle
   This voucher entitles the bearer to a 20% discount on frozen goods.
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. 1836, The New Sporting Magazine, (Please provide the book title or journal name), volume 11, page 227
4. (advertising) 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. 2014, Nigel Linacre, Advertising for Account Holders (RLE Marketing), page 9
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.