vow (n.) Look up vow at Dictionary.com
c.1300, from Anglo-French and Old French vou, from Latin votum "a vow, wish, promise, dedication," noun use of neuter of votus, past participle of vovere "to promise solemnly, pledge, dedicate, vow," from PIE root *ewegwh- "to speak solemnly, vow" (cf. Sanskrit vaghat- "one who offers a sacrifice;" Greek eukhe "vow, wish," eukhomai "I pray").
vow (v.) Look up vow at Dictionary.com
c.1300, from Old French vouer, from vou (see vow (n.)). Related: Vowed; vowing.