Origins
The word 'monastery' contains a paradox. It means a place where people live together in community, yet it derives from a Greek root meaning 'alone.' This contradiction is not a linguistic accident but a historical record, preserving the memory of how Christian monasticism evolved from solitary asceticism to communal life.
The Greek root is 'μόνος' (monos), meaning 'alone, single, solitary.' This root is among the most productive in the English vocabulary: 'monologue' (speaking alone), 'monopoly' (selling alone), 'monocle' (one-eyed lens), 'monochrome' (one color), 'monotone' (one tone), 'monarch' (sole ruler), 'monogamy' (marriage to one), and dozens more.
From 'monos' came the verb 'μονάζειν' (monazein), meaning 'to live alone,' and from that the noun 'μοναστήριον' (monastḗrion), meaning 'a place where one lives alone' — a hermit's cell. The word entered Latin as 'monastērium' and from there into all the Romance languages and into English.
Development
The historical context explains the paradox. In the third and fourth centuries CE, the deserts of Egypt, Syria, and Palestine became home to Christian ascetics who withdrew from society to pursue spiritual perfection in solitude. The most famous was St. Anthony of Egypt (c. 251–356), whose biography by Athanasius of Alexandria became one of the most influential texts in Christian history. These 'desert fathers' (and mothers) lived alone in caves and huts — they were 'monazōntes,' people who lived alone, and their dwellings were 'monastēria.'
The transformation from solitary to communal monasticism began with St. Pachomius (c. 292–348), an Egyptian who around 320 CE organized scattered hermits into a communal settlement at Tabennisi in Upper Egypt, governed by a common rule. Pachomius's innovation — shared meals, shared prayer, shared labor, under a common authority — was the birth of cenobitic monasticism (from Greek 'koinos bios,' common life). St. Basil of Caesarea (330–379) developed the model further in the East, and St. Benedict of Nursia (c. 480–547) established the Rule of St. Benedict, which became the foundation of Western monasticism.
Throughout this evolution, the word 'monastērium' traveled with the institution, even as its literal meaning became increasingly inappropriate. A Benedictine abbey housing a hundred monks was still called a 'monastery' — a 'place for being alone.' The word preserved the memory of the institution's origins even as the institution itself transformed.
Latin Roots
The word 'monk' has the same etymology. It comes from Late Latin 'monachus,' from Greek 'μοναχός' (monakhos), meaning 'one who lives alone.' A 'monk' is, etymologically, a solitary — even when he lives in a community of hundreds. And 'nun' — while its etymology is different (from Late Latin 'nonna,' an elderly woman, a title of respect) — often lives in a 'monastery' or 'convent,' the latter from Latin 'conventus' (a coming together), which at least has the honesty to acknowledge the communal nature of the life.
German took a different path. Instead of borrowing from Greek 'monos,' German uses 'Kloster' for monastery, from Latin 'claustrum' (an enclosed space, a lock), the same root that gives English 'cloister' and 'claustrophobia.' The German word emphasizes enclosure rather than solitude — a different aspect of monastic life, but one that is actually more accurate for a communal institution.