Emily Dickinson Lexicon

VOUCH'ER, n.

1. One who gives witness or full attestation to any thing. The great writers of that age stand up together as vouchers for each other's reputation. – Spectator.
2. In law, the act of calling in a person to make good his warranty of title.
3. A book, paper or document which serves to vouch the truth of accounts, or to confirm and establish facts of any kind. The merchant's books are his vouchers for the correctness of his accounts. Notes, bonds, receipts and other writings, are used as vouchers in proving facts.