Vouch

verb (used without object)
1.
to support as being true, certain, reliable, etc. (usually followed by for):
Her record in office vouches for her integrity.
2.
to attest; guarantee; certify (usually followed by for):
to vouch for someone in a business transaction.
verb (used with object)
3.
to sustain or uphold by, or as if by, practical proof or demonstration.
4.
(formerly) to call or summon (a person) into court to make good a warranty of title.
5.
to adduce or quote in support, as extracts from a book or author; cite in warrant or justification, as authority, instances, facts, etc.
6.
Archaic. to warrant or attest; to support or authenticate with vouchers.
7.
Archaic. to declare as with warrant; vouch for.
8.
Obsolete. to call or take as a witness.
noun, Obsolete.
9.
a vouching; an assertion.
10.
a formal attestation; a supporting warrant.
verb
1.
(intransitive) usually foll by for. to give personal assurance; guarantee: I’ll vouch for his safety
2.
when tr, usually takes a clause as object; when intr, usually foll by for. to furnish supporting evidence (for) or function as proof (of)
3.
(transitive) (English legal history) to summon (a person who had warranted title to land) to defend that title or give up land of equal value
4.
(transitive) (archaic) to cite (authors, principles, etc) in support of something
5.
(transitive) (obsolete) to assert
noun
6.
(obsolete) the act of vouching; assertion or allegation