vow
noun
°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."
°A declaration or assertion.
verb
°To make a vow.
°To declare publicly that one made a vow, usually to show one's determination or to announce an act of retaliation.