v. 1 intr. (foll. by for) answer for, be surety for (will vouch for the truth of this; can vouch for him; could not vouch for his honesty). 2 tr. archaic cite as an authority. 3 tr. archaic confirm or uphold (a statement) by evidence or assertion.
[ ME f. OF vo(u)cher summon etc., ult. f. L vocare call ]