voucher (n.)youdaoicibaDictYouDict[voucher 词源字典]
1520s, originally "summoning of a person into court to warrant the title to a property, a calling to vouch;" see vouch. Meaning "receipt from a business transaction" is first attested 1690s; sense of "document which can be exchanged for goods or services" is attested from 1947.[voucher etymology, voucher origin, 英语词源]