Sister (Catholic)

A nun is a member of a religious community of women, typically one living under vows of poverty, chastity, and obedience. She may have decided to dedicate her life to serving all other living beings, or she might be an ascetic who voluntarily chose to leave mainstream society and live her life in prayer and contemplation in a monastery or convent. The term "nun" is applicable to Catholics (eastern and western traditions), Orthodox Christians, Anglicans, Lutherans, Jains, Buddhists, Taoists, Hindus and some other religious traditions.

While in common usage the terms "nun" and "sister" are often used interchangeably (the same title of "Sister" for an individual member of both forms), they are considered different ways of life, with a "nun" being a religious woman who lives a contemplative and cloistered life of meditation and prayer for the salvation of others, while a "religious sister", in religious institutes like St. Mother Teresa's Missionaries of Charity, lives an active vocation of both prayer and service, often to the needy, ill, poor, and uneducated.

All Buddhist traditions have nuns, although their status is different among Buddhist countries. The Buddha is reported to have allowed women into the sangha only with great reluctance, predicting that the move would lead to Buddhism's collapse after 500 years, rather than the 1,000 years it would have enjoyed otherwise. (This prophecy occurs only once in the Canon and is the only prophecy involving time in the Canon, leading some to suspect that it is a late addition.) Fully ordained Buddhist nuns (bhikkhunis) have more Patimokkha rules than the monks (bhikkhus). The important vows are the same, however.

...
Wikipedia