Vow
Middle English: from Old French vou, from Latin votum (see vote); the verb is from Old French vouer .
wiktionary
From Middle English vowe, voue, that from Old French vut, in turn from Latin vōtum(“a promise, dedication, vow”), from vovēre(“to promise, vow”). Doublet of vote.
etymonline
vow (n.)
"solemn promise," c. 1300, from Anglo-French and Old French voe (Modern French vœu), from Latin votum "a promise to a god, solemn pledge, dedication; that which is promised; a wish, desire, longing, prayer," noun use of neuter of votus, past participle of vovere "to promise solemnly, pledge, dedicate, vow," from PIE root *wegwh- "to speak solemnly, vow, preach" (source also of Sanskrit vaghat- "one who offers a sacrifice;" Greek eukhe "vow, wish," eukhomai "I pray"). Meaning "solemn engagement to devote oneself to a religious order or life" is from c. 1400; earlier "to bind oneself" to chastity (early 14c.).
vow (v.)
"promise solemnly," c. 1300, from Old French voer, from voe (see vow (n.)). Related: Vowed; vowing.
