avouch

To declare freely and openly; to assert.

Neither indeede would I have thought, that any such antiquities could have been avouched for the Irish, that maketh me the more to long to see some other of your observations, which you have gathered out of that country […]

If this which he avouches does appear, There is nor flying hence nor tarrying here.

To acknowledge deliberately; to admit; to confess; to sanction.

Thou hast avouched the Lord this day to be thy God, and to walk in his ways, and to keep his statutes, and his commandments, and his judgments, and to hearken unto his voice: And the Lord hath avouched thee this day to be his peculiar people, as he hath promised thee, and that thou shouldest keep all his commandments;

[…] send me that hag hither; she shall avouch what it was that she hath given to the wretch Dryfesdale, or the pilniewinks and thumbikins shall wrench it out of her finger-joints.

To confirm or verify, to affirm the validity of.

For ([…] as the sorowfull dooings of our present dayes do too certeinly avouch) greate men hurt not the common weale so much by beeing evil in respect of themselves, as by drawing others unto evil by their evil example.

As a great public document, addressed to the whole Christian world by him who aspired to be the first ecclesiastic, we might be disposed to question its authenticity, if it were not avouched by the full evidence in its favour and its agreement with all the events of the period.

To appeal to; to cite or claim as authority.

And for proofe of their opinion they avouch many successions of authorities that no fee simple should passe before the condition performed.

evidence; declaration

Before my God, I might not this believe Without the sensible and true avouch Of mine own eyes.