Within Roman Catholicism, a monk is a member of a religious order who lives a communal life in a monastery, abbey, or priory under a monastic rule of life (such as the Rule of St. Benedict) and under the vows of poverty, chastity, and obedience. St. Benedict of Nursia is considered to be the founder of western monasticism. He established the first monastic community in the west and authored the Rule of St. Benedict, which is the foundation for the Order of St. Benedict and all of its reforms such as the Cistercians and the Trappists.
Rev. C. Arthur Lane Illustrated Notes on English Church History (London: Society for Promoting Christian Knowledge, 1901)