Source : Webster's Revised Unabridged Dictionary (1913)

Vow \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.

Vow \Vow\, n. [OE. vou, OF. vou, veu, vo, vu, F. v?u, 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.

Vow \Vow\, v. t. [imp. & p. p. {Vowed}; p. pr. & vb. n.
   {Vowing}.] [OE. vouen, OF. vouer, voer, F. vouer, LL. votare.
   See {Vow}, n.]
   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.

Source : WordNet®

vow
     n : a solemn pledge (to oneself or to another or to a deity) to
         do something or to behave in a certain manner; "they took
         vows of poverty"
     v 1: make a vow; promise; "He vowed never to drink alcohol again"
     2: dedicate to a deity by a vow [syn: {consecrate}]