To declare publicly that one has made a vow, usually to show one's determination or to announce an act of retaliation.
Esimerkit
The old hermit, up in the mountains, took a vow of silence.
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.
When thou vowest a vow unto God, defer not to pay it.
We do not vow that we will never sin, nor neglect a duty (nor ought we to do so).