vow-n; 2 Senses

Sense Number 1: a speaker's solemn declaration that binds them to a commitment

Commentary: VOW[+event][+speech_act][+declaration][+single][+commitment][+binding][+solemn]

Our vow to our customers is that we are here to serve their needs.
We didn't really believe Mary's vow that she would never eat another piece of fudge.
The king made his knights make a vow of allegiance to him.

PropBank: vow.01
WordNet 3.0 Sense Numbers: 1

Sense Number 2: a set of solemn declarations that commit the speaker to a prescribed role in life, e.g., marriage

Commentary: VOW[+event][+speech_act][+declaration][+multiple][+commitment][+binding][+solemn][+role][+prescribed]
NOTE: this sense usually occurs in the plural

Mary and John wrote their own wedding vows.
These nuns have taken the vow of silence.
The young priest broke his vows of celibacy and poverty.

PropBank: vow.01
WordNet 0.0 Sense Numbers: 2