means Solemn, binding promises—especially the formal ones spoken at a wedding or on entering religious life.

from From Old French 'vou' or 'vo,' which came from Latin 'votum,' meaning a vow, promise, or thing solemnly pledged to a god. 'Votum' was itself born from 'vovere,' 'to vow' or 'to dedicate'—the same root that gives us 'devote' and 'votive' (as in a votive candle, a little flame standing in for a promise made). At its heart, a vow was always something offered upward, a word given that you didn't expect to take back.