Webster's Revised Unabridged Dictionary · 1913

Vouch

Vouch , transitive verb

[Old English vouchen, Old French vochier to call, from Latin vocare to call, from vox, vocis, voice. See Voice, and compare Avouch.]

1.
To call; to summon. [Obsolete]
[They] vouch (as I might say) to their aid the authority of the writers. — Sir T. Elyot
2.
To call upon to witness; to obtest.
Vouch the silent stars and conscious moon. — Dryden
3.
To warrant; to maintain by affirmations; to attest; to affirm; to avouch.
They made him ashamed to vouch the truth of the relation, and afterwards to credit it. — Atterbury
4.
To back; to support; to confirm; to establish.
Me damp horror chilled At such bold words vouched with a deed so bold. — Milton
5.
(Law) To call into court to warrant and defend, or to make good a warranty of title.
He vouches the tenant in tail, who vouches over the common vouchee. — Blackstone

Vouch , intransitive verb

1.
To bear witness; to give testimony or full attestation.
He will not believe her until the elector of Hanover shall vouch for the truth of what she has... affirmed. — Swift
2.
To assert; to aver; to declare. — Shakespeare

Vouch , noun

Warrant; attestation. [Obsolete]
The vouch of very malice itself. — Shakespeare