(Claustrum), a habitation surrounded with walls, and inhabited by canons or religious, &c. In a more general sense, cloister is used for a mona- stery of religious, of either sex. In a more restrain- ed sense, cloister is used for the principal part of a re- gular monastery, consisting of a square built around; ordinarily between the church, the chapter-house, and the refectory; and over which is the dormitory. The cloisters served for several purposes in the ancient mo- nasteries. Petrus Blesensis observes that it was here the monks held their lectures: the lecture of morali- ty at the north side, next the church; the school on the west, and the chapter on the east; spiritual medi- tation, &c. being reserved for the church. Lanfranc observes, that the proper use of the cloister was for the monks to meet in, and converse together, at cer- tain hours of the day.

The form of the cloister was square; and it had its name claustrum, from claudo, "I shut or close;" as being inclosed on its four sides with buildings. Hence in architecture, a building is still said to be in form of a cloister, when there are buildings on each of the four sides of the court.