voucher

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A piece of substantiating evidence; a proof.
• noun A written record of expenditure, disbursement, or completed transaction.
• noun A written authorization or certificate, especially one exchangeable for cash or representing a credit against future expenditures.
• transitive verb To substantiate or authenticate with evidence.
• transitive verb To prepare a voucher for.
• transitive verb To issue a voucher to.

from The Century Dictionary.

• noun One who vouchės, or gives attestation or confirmation; one who is surety for another.
• noun A book, paper, document, or stamp which serves to prove the truth of accounts, or to confirm and establish facts of any kind; specifically, a receipt or other written evidence of the payment of money.
• noun In old English law: The tenant in a writ of right; one who called in another to establish his warranty of title. In common recoveries there might be a single voucher or double vouchers. [Also written vouchor.] The calling in of a person to vouch.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who vouches, or gives witness or full attestation, to anything.
• noun A book, paper, or document which serves to vouch the truth of accounts, or to confirm and establish facts of any kind; also, any acquittance or receipt showing the payment of a debt.
• noun The act of calling in a person to make good his warranty of title in the old form of action for the recovery of lands.
• noun The tenant in a writ of right; one who calls in another to establish his warranty of title. In common recoveries, there may be a single voucher or double vouchers.
• noun A document attesting to a credit against certain defined expenditures; a recipt for prepayment; -- often used in pre-arranged travel plans, to provide evidence of pre-payment of the cost of lodging, transportation, or meals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A piece of paper that entitles the holder to a discount, or that can be exchanged for goods and services.
• noun A receipt.
• noun A person who vouches.
• verb transitive To establish the authenticity of; to vouch for.
• verb transitive To provide a vouch for (an expenditure).
• verb transitive To provide (a beneficiary) with a voucher.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a negotiable certificate that can be detached and redeemed as needed
• noun someone who vouches for another or for the correctness of a statement
• noun a document that serves as evidence of some expenditure