Religious sister

A religious sister (abbreviated: Sr.)[1][2] in the Catholic Church is a woman who has taken public vows in a religious institute dedicated to apostolic works, as distinguished from a nun who lives a cloistered monastic life dedicated to prayer and labor, or a canoness regular, who provides a service to the world, either teaching or nursing, within the confines of the monastery.

The HarperCollins Encyclopedia of Catholicism (1995) defines "congregations of sisters [as] institutes of women who profess the simple vows of poverty, chastity, and obedience, live a common life, and are engaged in ministering to the needs of society.

Nuns recite the Liturgy of the Hours or Divine Office in common [...] [and] live a contemplative, cloistered life in a monastery [...] behind the 'papal enclosure'.

In 1521, Pope Leo X allowed tertiaries of religious orders to take simple vows and live a more active life dedicated to charitable works.

[3]: 1101  After nearly three centuries, in 1900 Pope Leo XIII by his constitution Conditae a Christo gave his approval to these congregations with simple vows.

[15] Throughout the post-Vatican II document Ecclesiae Sanctae (1967), Pope Paul VI used the word "nun" to refer to women with solemn vows.

The former Superior General of the Sisters of Providence of Saint Mary-of-the-Woods , Sister Ann Margaret O'Hara , SP, in 2006. In the background a painting of the congregation's foundress, Mother Théodore Guérin .
Sisters (with chaplain) working at Mother of Peace AIDS orphanage in Zimbabwe , to prepare for opening another orphanage