Atype of religious life in which men or women leave the secular world and enter a convent or monastery to devote themselves to prayer, contemplation, and self-denial in solitude.

The answer is Monasticism (Monkhood)

Explanation:

The question itself already gives a description of this kind of religious practice. The monastic enclosure is an expression that refers to the way practitioners receive the vow and agree not to leave their monastery or convent anymore. The enclosure is intended to keep all followers in a state of silence and prayer and other ascetic resources for perfect union with God. Despite their separation from the world, their followers never failed to unite intimately with humanity, always offering their prayers in the form of intercession. Monastic life is founded on the renunciation of the world to overcome and to find what is above this nature.