History And The Modern Nun-Sister Distinction

Female monasticism developed alongside male monasticism from the early Christian centuries, with double monasteries, communities combining monks and nuns under a single abbess or abbot, common in the early medieval period in regions including Anglo-Saxon England and Merovingian Gaul before falling out of favor as later canon law increasingly required separate governance and stricter enclosure for women's communities specifically, a divergence reflecting the medieval church's generally more restrictive approach to women's public religious authority compared with men's. Enclosure requirements for nuns were significantly formalized by the Council of Trent in the sixteenth century, partly in response to concerns about the independence some women's communities had exercised, a formalization that shaped the strict cloister many people today associate with the word nun.

The modern distinction between nuns, of solemn vows and enclosure, and sisters, of simple vows and active ministry, though juridically clear in canon law, has become less significant in everyday usage and even within some communities' own self-description, particularly as many historically active congregations of sisters, teaching orders and nursing orders founded especially in the eighteenth and nineteenth centuries, vastly outnumber traditionally cloistered nuns in the contemporary Catholic Church, especially in mission territories and the developing world where such congregations have seen the most vocations growth in recent decades.