【Religious】 ,  【monk】 ,  【friar】 ,  【nun】  all mean a member of a 【religious】 order whose members are bound by the monastic vows of poverty, chastity, and obedience and who lead to a greater or lesser extent a cloistered life.

【Religious】  is the comprehensive term applicable either to a man or a woman; it implies a living apart from the world either in a cloistered community formed of members of the same order or as a hermit, (see RECLUSE ) under the governance of the superior of an order.

【Monk】  in general use may designate a male 【religious】 ; in precise technical use the term applies to a member of a 【religious】 order for men (as the Benedictine or Cistercian order) whose members live an ascetic life in a cloistered community, and devote themselves mainly to contemplation and prayer and liturgical observances, and to some assigned and usually scholarly, artistic, or scientific employment.

【Friar】  applies to a member of a mendicant order under whose original regulations neither personal nor community tenure of property was allowed and whose members lived by alms and wandered from place to place preaching the Gospel and administering the sacraments or to a member of an order patterned after them, whether he lives as a mendicant or in a cloistered community and whether he serves as a pastor, a curate, a missionary, a preacher, or a teacher.

【Nun】  applies only to a female 【religious】 ; since there are no terms to distinguish nuns according to the severity of their discipline, the rigor of their cloistered life, and the nature of their duties, the word is generally applied to any member of a 【religious】 order of women who devote themselves to prayer, contemplation, and work, and may wear a habit.