A promise made to God voluntarily; a solemn commitment to do or not do something, e.g. a vow of chastity taken after the death of wife or husband was not uncommon in the 13c and after. Monks took three vows: the vow to poverty was against the deceits of the world; that to chastity was against the lusts and disturbances of the flesh; that to obedience was against the tricks and snares of the devil. -
Cf. Incontinence
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.