cloisteryoudaoicibaDictYouDict[cloister 词源字典]
cloister: [13] A cloister was originally simply an enclosed place, a ‘close’. The word comes from Old French cloistre, a descendant of Latin claustrum ‘bar, bolt, enclosure’, which was formed from the past participial stem of Latin claudere ‘close’ (source of English close). The notion of ‘enclosure’ led to the word’s being applied to a place of religious seclusion, such as a monastery or convent, and hence to a covered walkway within a monastic building. It also lies behind claustrophobia [19], which was formed from Latin claustrum.
=> claustrophobia, close[cloister etymology, cloister origin, 英语词源]
cloister (n.)youdaoicibaDictYouDict
early 13c., from Old French cloistre "monastery, convent; enclosure" (12c., Modern French cloître), from Medieval Latin claustrum "portion of monastery closed off to laity," from Latin claustrum (usually in plural, claustra) "place shut in, enclosure; bar, bolt, means of shutting in," from past participle stem of claudere (see close (v.)).

"The original purpose of cloisters was to afford a place in which the monks could take exercise and recreation" [Century Dictionary]. Spelling in French influenced by cloison "partition." Old English had clustor, clauster in the sense "prison, lock, barrier," directly from Latin, and compare, from the same source, Dutch klooster, German Kloster, Polish klasztor.
cloister (v.)youdaoicibaDictYouDict
c. 1400 (implied in cloistered), from cloister (n.). Figurative use from c. 1600. Related: Cloistered; cloistering.