1. A piece of substantiating evidence; a proof.

2. A written record of expenditure, disbursement, or completed transaction.

3. A written authorization or certificate, especially one exchangeable for cash or representing a credit against future expenditures.

1. To substantiate or authenticate with evidence.

2. To prepare a voucher for: properly vouchering each transaction.

3. To issue a voucher to: a company that vouchers employees when the payroll cannot be met.