To take responsibility for; to express confidence in; to witness; to obtest.
To warrant; to maintain by affirmations
I can vouch that the match took place.
To back; to support; to confirm.
To call into court to warrant and defend, or to make good a warranty of title.
To call; to summon.
To bear witness; to give testimony or full attestation.
To call as a witness.
To assert; to aver; to declare.