What does "vow" mean?

Additional senses

1. 2.Specifically, a promise of fidelity; a pledge of love or affection; as, the marriage vow. Knights of love, who never broke their vow; Firm to their plighted faith. Dryden.
2. 3.To give, consecrate, or dedicate to God, or to some deity, by a solemn promise; to devote; to promise solemnly. "When thou vowest a vow unto God, defer not to pay it." Eccl. v.
3. 4.[Men] that vow a long and weary pilgrimage. Shak.
4. 5.To assert solemnly; to asseverate.
5. 6.To make a vow, or solemn promise. Better is it that thou shouldest not vow, than that thou shouldest vow and not pay. Eccl. v. 5.