A vow of celibacy.
priests have three vows: the vow of poverty, chastity, and obedience. the vow of chastity professes their singleness.
No. Because they take a vow of chastity.
Chastity is a vow of sorts, most likely meaning the vow of virginity, and to protect that would mean to protect her vow of virginity, or innocence.
Like priests, nuns take a vow of chastity
The Jesuits take the normal vows of poverty, chastity and obedience. They also make a fourth vow of special obedience to the Pope.
A married couple, if they both decided of their own free will to practice chastity, and with the permission of their confessors or priest, could take a vow of chastity. But it would probably just be a private vow, unless they were seeking to enter religious Orders or the priesthood. This has been done by some couples in history where the wife entered a convent, and the husband entered the priesthood.
A vow of poverty is a vow before God to not own anything or have any money. Nuns, religious priests, sisters, and brothers take this vow in addition to vows of chastity and obedience. These three vows are known as the evangelical counsels.
She had made a vow of chastity so remaining a virgin was very important to her.
That's a question that is not easily generalized. Any lay person may take a vow of chastity. Married persons may take the vow of chastity, as permanent deacons do, where if the spouse dies, they may not remarry. The Norbertine tertiaries may be married or single. Their web page is listed below.
Catholic priests in the Latin Rite of the Church take promises of celibacy.
Catholic clergy make a vow of chastity - no sex.