The Collaborative International Dictionary of English v.0.48:

Monastery \Mon"as*te*ry\, n.; pl. Monasteries. [L.
   monasterium, Gr. ?, fr. ? a solitary, a monk, fr. ? to be
   alone, live in solitude, fr. mo`nos alone. Cf. Minister.]
   A house of religious retirement, or of secusion from ordinary
   temporal concerns, especially for monks; -- more rarely
   applied to such a house for females.
   [1913 Webster]

   Syn: Convent; abbey; priory. See Cloister.
        [1913 Webster]

WordNet (r) 3.0 (2006):

monastery
    n 1: the residence of a religious community