vow

Etymology

From Middle English vowe, voue, that from Old French vut, in turn from Latin vōtum (“a promise, dedication, vow”), from vovēre (“to promise, vow”). Not related to avow. Doublet of vote.

noun

1. A solemn promise to perform some act, or behave in a specified manner, especially a promise to live and act in accordance with the rules of a religious order.
   The old hermit, up in the mountains, took a vow of silence.
2. A declaration or assertion.
   Swearing doesn't just mean what we now understand by "dirty words". It is entwined, in social and linguistic history, with the other sort of swearing: vows and oaths. Consider for a moment the origins of almost any word we have for bad language – "profanity", "curses", "oaths" and "swearing" itself. 2013-06-14, Sam Leith, “Where the profound meets the profane”, in The Guardian Weekly, volume 189, number 1, page 37
3. (obsolete) A votive offering.
   There are also waxen vows, that represent other parts of the body mixed with them; but of these there are few in comparison of the number of the Priapi. 1786, Richard Payne Knight, The Worship of Priapus

verb

1. (transitive, intransitive) To make a vow; to promise.
   We do not vow that we will never sin, nor neglect a duty (nor ought we to do so). 1673, Richard Baxter, Christian Directory
2. (transitive) To make a vow regarding (something).
   The wronged woman vowed revenge.
3. To declare publicly that one has made a vow, usually to show one's determination or to announce an act of retaliation.
   The rebels vowed to continue their fight.