What's The Oldest Order Of Roman Catholic Nuns?

With three exceptions mentioned below, the Benedictines, (Benedictine article at New Advent) begun by St. Benedict (480-543 AD) are the oldest continuous religious order of monks and nuns in the Roman Catholic Church. St. Benedict is the father of western monasticism (St. Benedict Biography).  For the source of this answer about Benedictines being the oldest order see:

John J. Kenny, Now that you are a Catholic an informal guide to Catholic customs, traditions, and practices (New York: Paulist P, 2003) pg. 90.

"Suitable habits for Benedictine monks and nuns." Web log post. Suitable habits for Benedictine monks and nuns. 11 July 2008. 22 Nov. 2009 <>.

However, as a first exception it might be said that the Benedictines are not an Order in the most technical sense of the word because of their independence and lack of a formalized hierarchical structure.  But in the sense that most people mean — the Benedictines are an Order of the Catholic Church.

See, for example, this quote from the Benedictine article at New Advent:

“The term Order as here applied to the spiritual family of St. Benedict is used in a sense differing somewhat from that in which it is applied to other religious orders. In its ordinary meaning the term implies one complete religious family, made up of a number of monasteries, all of which are subject to a common superior or "general" who usually resides either in Rome or in the mother-house of the order, if there be one. It may be divided into various provinces, according to the countries over which it is spread, each provincial head being immediately subject to the general, just as the superior of each house is subject to his own provincial. This system of centralized authority has never entered into the organization of the Benedictine Order. There is no general or common superior over the whole order other than the pope himself, and the order consists, so to speak, of what are practically a number of orders, called "congregations", each of which is autonomous; all are united, not under the obedience to one general superior, but only by the spiritual bond of allegiance to the same Rule, which may be modified according to the circumstances of each particular house or congregation. It is in this latter sense that the term Order is applied in this article to all monasteries professing to observe St. Benedict's Rule.”

As a second exception, the Carmelites (such as here) trace their roots back to the time before Christ to the prophets Elias (Elijah ) and Eliseus (Elisha) and their time at Mount Carmel in the Holy Land.  Other researchers note that:

“The silence of Palestine pilgrims previous to A.D. 1150, of chroniclers, of early documents, in one word the negative evidence of history has induced modern historians to disregard the claims of the order, and to place its foundation in or about the year 1155 when it is first spoken of in documents of undoubted authenticity.”

The third exception is by far the most important.

How do we define an Order of Nuns?

If we use what has come to be known as Orders in the Catholic church today, those type of orders seem to extend back to the time of the Benedictines (while recognizing the technical distinction mentioned above), but if we have a slightly more expanded definition to include any form in which the Church recognized women as living a life in a somewhat different manner than other Christians, such as consecrated virgins, then those religious women were known at the time of the apostles — in essence they go back to very beginning of the Church.

The following quote from New Advent is relevant to highlight that when we speak of a different form of religious life — women came before men and women saw that vision first.

“The institution of nuns and sisters, who devote themselves in various religious orders to the practice of a life of perfection, dates from the first ages of the Church, and women may claim with a certain pride that they were the first to embrace the religious state for its own sake, without regard to missionary work and ecclesiastical functions proper to men. St. Paul speaks of widows, who were called to certain kinds of church work (1 Timothy 5:9), and of virgins (1 Corinthians 7), whom he praises for their continence and their devotion to the things of the Lord. The virgins were remarkable for their perfect and perpetual chastity which the Catholic Apologists have extolled as a contrast to pagan corruption .... Many also practiced poverty. From the earliest times they were called the spouses of Christ, according to St. Athanasius, the custom of the Church ....

“St. Cyprian describes a virgin who had broken her vows as an adulteress .... Tertullian distinguishes between those virgins who took the veil publicly in the assembly of the faithful, and others known to God alone; the veil seems to have been simply that of married women. Virgins vowed to the service of God, at first continued to live with their families, but as early as the end of the third century there were community houses known as partheuones; and certainly at the beginning of the same century the virgins formed a special class in the Church, receiving Holy Communion before the laity. The office of Good Friday in which the virgins are mentioned after the porters, and the Litany of the Saints, in which they are invoked with the widows, shows traces of this classification. They were sometimes admitted among the deaconesses for the baptism of adult women and to exercise the functions which St. Paul had reserved for widows of sixty years.”