The Meaning of the Terms Nun, Sister, Monk, Priest, and Brother

These terms are indeed confusing, because they are often used interchangeably even though they have technical differences. First, let's look at the difference between nuns and sisters. A nun is a woman who belongs to a religious order and takes the vows of poverty, chastity, and obedience. Their vows are publicly accepted by superiors in the name of the Church and solemn. In general, solemn vows are professed by members of religious orders after a period of temporary, simple vows. When bound by solemn vows, a woman is a nun but is commonly called "Sister" (although some orders use another formal title, like "Dame" or "Mother"); when bound by simple vows, a woman is a sister, not a nun, and thereby called "Sister." Nuns recite the Liturgy of the Hours or Divine Office in common, and engage in some work to help support themselves.

Another distinguishing mark of nuns is that they live a contemplative, cloistered life in a monastery. "Cloistered" refers to living within the confines of the monastery behind the "papal enclosure." Nuns are permitted to leave the cloister only under special circumstances and with the proper permission. Moreover, visitors are not be permitted to enter into the cloistered area. When visiting these monasteries, like the Poor Clares' Monastery in Alexandria, a person may enter the public area of the chapel, but a wrought-iron screen separates it from the nun's side or "cloistered" side of the chapel. Also when visiting one of the nuns, the visitor is physically separated by a grill or other barrier from the nun who is in the cloister. Besides the Poor Clares, other strictly cloistered nuns are the Carmelites and Benedictines.

In some cases, the cloister restrictions are not as strictly enforced. Some orders of nuns, while technically cloistered, conduct works of charity or education, interacting with the public. For example, the Visitation Sisters are technically cloistered nuns but teach school.

With this understanding of the term "nun," the title "Sister" denotes a woman religious under simple vows, who is a member of a particular religious congregation. (The distinction between a "solemn vow" and a "simple vow" is a determination made by the Church when the religious community is established: members of religious orders make a final profession of solemn vows, and members of religious institutes or religious congregations make a final profession of perpetual simple vows, after a period of temporary simple vows.) These women religious also take the vows of poverty, chastity, and obedience; live in community in a convent; and share in a particular apostolate. These religious congregations may serve either a particular diocese under the immediate jurisdiction of the local bishop, or serve throughout the universal Church under the immediate jurisdiction of the Pope. Examples of these communities are the Sisters, Servants of the Immaculate Heart of Mary, Sisters of the Holy Cross, and Daughters of St. Paul.

Since the 6th century, monks and nuns following the Rule of Saint Benedict have been making the so-called Benedictine vow at their public profession of obedience (placing oneself under the direction of the abbot/abbess or prior/prioress), stability (committing oneself to a particular monastery), and "conversion of manners" (which includes forgoing private ownership and celibate chastity). A monk may be a priest or a deacon, who has received the Sacrament of Holy Orders, or a religious brother, who is not ordained. Monks live in a monastery, the word from which "monk" is derived. Depending upon the circumstances of the particular order, they may have a very strict contemplative, cloistered lifestyle, like the Order of Cistercians of Strict Observance (commonly known as the Trappists), or a less strictly cloistered lifestyle, like the Benedictines.

Just as an aside, these monasteries are referred to as abbeys when they are independent, self-sufficient, and have a certain number of monks or nuns. The head of the abbey is either the abbot or abbess.

Moreover, religious institutes or congregations of men include those of both priests and brothers, like the Oblates of St. Francis de Sales, and those of only brothers, like the Brothers of the Sacred Heart or Brothers of St. Francis Xavier. These men religious also take the simple vows of poverty, chastity, and obedience, live in community, and share in a particular apostolate, like education, health care, or other charitable work.

While this article has dealt with the fine distinctions of terminology, we must not forget that these individuals have totally dedicated their lives to God; taken the vows of poverty, chastity and obedience; serve the Church in special way; work for the salvation of the world; and strive for the perfection of charity in their own lives. They are an outstanding sign of the Church, and a witness to Jesus Christ.