Etymology
1. c.1325, "summon into court to prove a title," from Anglo-Fr.
voucher, O.Fr.
vocher "to call, summon, invoke, claim," probably from Gallo-Romance
*voticare, metathesis of L.
vocitare "to call to, summon insistently," frequentative of L.
vocare "to call, call upon, summon" (see voice). Meaning "guarantee to be true or accurate" is first attested 1591.
2. The verb is derived from Middle English vouchen (“to call, summon; to provide; to make available, proffer; to affirm, declare formally”) [and other forms], from Anglo-Norman vocher, voucher, woucher, and Old French vocher, voucher, vochier (“to call, summon; to claim; to call upon, invoke; to denounce”) [and other forms], from Vulgar Latin *vocicāre, derived from Latin vocāre (“to call, summon; to call upon, invoke; to designate, name; to bring or put (into a condition or state”), ultimately from Proto-Indo-European *wekʷ- (“to sound out; to speak”).
3. Verb sense 8.1 (“to summon (someone) into court to establish a warranty of title to land”) in the form vouch to warrant or vouch to warranty is a calque from Anglo-Norman and Old French voucher a garant.
4. The noun is derived from the verb. See: Old French '
vochier', Latin '
voco'.