Prior to the profound changes that took place in society and the Catholic church in the 1960s, Catholic nuns were idenfiable regardless of their order because they all wore long black, white or grey dresses and long headdress which may have been called a bonnet, depending on the traditions of their order. Their rosaries and crucifixes were additional symbols of their dedication to the Gospel and their separation from the world. Modern nuns do not always adhere to such recognisable traditional garments.
The older style nun's outfit consisted of a simple tunic with long sleeves, usually worn over a lighter weight dress, also with long sleeves. This tunic was sometimes partially covered with an apronlike drape. All the garments were floor length. Over the tunic, all nuns wore a woven belt to which the rosary was hooked and they wore a crucifix suspended on a cord around their necks. The outfit was always topped with a headdress that obscured the hair and ears completely. Depending on climatic conditions, cotton might replace wool and dresses might be shorter.
Symbolic of Separation
A nun's habit, like a priest's garb, was intended to promote absolute uniformity of appearance as well as separation from worldly concerns like vanity and individuality. Signalling their devotion and dedication to the Gospel and to serving God, the uniqueness of their outfits promoted trust among those they contacted in the outside world and helped them with a constant awareness of their higher purpose.
The rosary used by nuns was a chain of beads and metal links, sometimes measured in "decades" of 10 beads. These were used to mark the saying of certain prayers, sometimes as a form of meditation, sometimes as a pastime and occasionally as a form of penitence. In the traditional habit, the rosary was made of wooden beads and worn attached to the belt, either over or under the second layer of apron.
In church literature, the bonnet can be any traditional nun's headdress especially those of the Sisters of Charity which was adopted from a French peasant's costume. It was a stiffly starched, white apparatus that resembled wings. More commonly, many orders of nuns wore simple white caps to conceal very short hair or shaved scalps, covered the caps with white collars and long, face shielding cuffs and draped the rest with a black veil. Even the Sisters of Charity depicted in the film "Doubt" eventually adopted a black, shirred hat with wide ties beneath the chin as their bonnet.
Today's nuns may wear any sort of modest dress, even trousers, in their pursuits. They usually wear simple, plain clothing but that is not a requirement nor is head covering necessary. Generally, the only requirement is that they wear some symbol of their dedication, such as a crucifix which might be a pendant or a brooch.
Dominican sisters as well as some other orders still maintain cloistered orders of nuns who live in complete retirement from the rest of the world. Most of these nuns still wear the tradtional habit which is part of their absolute dedication to God.