Sister
The term has been applied to female Christians since the earliest NT times. The language of family kinship recalls the closeness of the bond that is shared by those who live in Christ. For example, the Gospel of Mk (3:35) records Jesus' statement that “Whoever does the will of God is my brother and sister and mother.” The term has been used more specifically to indicate a woman who is a member of a religious order or community. Historically, the term indicates a laywoman, but it is now also used by some priests in religious orders or communities as an expression of equality and community.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from “An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians,” Don S. Armentrout and Robert Boak Slocum, editors.