To affirm or acknowledge openly; declare or assert with positiveness; proclaim.To admit, confess, or avow.To maintain, vindicate, or justify; make good; answer for; establish; guarantee; substantiate.To appeal to, or cite as proof or warrant: as, to avouch the authorities on any subject.To give assurance or guaranty; vouch: as, “I can avouch for her reputation,”n. Evidence; testimony; assurance.