Vow, n.
Etymology: [OE. vou, OF. vou, veu, vo, vu, F. v, from L. votum, from vovere, to vow. Cf. Avow, Devout, Vote.]
1. 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. "Nothing . . . that may . . . stain my vow of Nazarite." Milton. I pray thee, let me go and pay my vow. 2 Sam. xv. 7. I am combined by a sacred vow. Shak.
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 other Webster entries under this spelling
Vow, v. t. [imp. & p. p. Vowed; p. pr. & vb. n. Vowing.]
1. 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. 4. [Men] that vow a long and weary pilgrimage. Shak.
2. To assert solemnly; to asseverate.
Vow, v. i.
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.