Etymology From Middle English avowen, from Old French avouer, from Latin advocare (“to call to, call upon, hence to call as a witness, defender, patron, or advocate”), from ad (“to”) + vocare (“to call”). Doublet of advoke, avouch, and advocate. Not related to vow.
1
To declare openly and boldly, as something believed to be right; to own, acknowledge or confess frankly.
[…] in 1786, and for some period later, there were few, if any, prominent Americans, who avowed themselves in favor of broadly democratic systems.1858, Henry Stephens Randall, The Life of Thomas Jefferson, volume 1, page 461:
2
To bind or devote by a vow.
No man may halewe and avowe the firste gendrid thingis that perteynen to the Lord, whether it is oxe, whether scheep, tho ben the Lordis part.c. 1382–1395, John Wycliffe [et al.], edited by Josiah Forshall and Frederic Madden, The Holy Bible, […], volume I, Oxford: At the University Press, published 1850, →OCLC, Leviticus 27:26, page 362, column 2:
3
Law To acknowledge and justify, as an act done. See avowry.
avow himself the accomplice of his crimes1765–1769, William Blackstone, Commentaries on the Laws of England, (please specify |book=I to IV), Oxford, Oxfordshire: […] Clarendon Press, →OCLC:
Etymology From Middle English avowen, from Old French avouer, from Latin advocare (“to call to, call upon, hence to call as a witness, defender, patron, or advocate”), from ad (“to”) + vocare (“to call”). Doublet of advoke, avouch, and advocate. Not related to vow.
without thy Knowledge and Avow1697, Virgil, “The Twelfth Book of the Æneis”, in John Dryden, transl., The Works of Virgil: Containing His Pastorals, Georgics, and Æneis. […], London: […] Jacob Tonson, […], →OCLC: