vow

n. Solemn, esp. Religious, promise (monastic vows; marriage vows). v. 1 promise solemnly. 2 archaic declare solemnly. [french vou(er): related to *vote]

n. A solemn promise made to God, or to some deity; an act by which one consecrates or devotes himself, absolutely or conditionally, wholly or in part, for a longer or shorter time, to some act, service, or condition; a devotion of one's possessions; as, a baptismal vow; a vow of poverty.