Definition of: vouch

(vouch) v.i.
1. To give one's own assurance or guarantee; bear witness: with for: I will vouch for their honesty.
2. To serve as assurance or proof: with for: The evidence vouches for his innocence.
—v.t.
3. To bear witness to; attest or affirm.
4. To cite as support or justification, as a precedent, authority, etc.
5. To uphold by satisfactory proof or evidence; substantiate.
6. Law To call upon or summon (a person) to defend a title.
7. Obs To call to witness.
—noun A declaration that attests; an assertion. [<OF vocher, voucher <L vocare call <vox, vocis a voice]