The Collaborative International Dictionary of English v.0.48:

Monasticism \Mo*nas"ti*cism\, n.
   The monastic life, system, or condition. --Milman.
   [1913 Webster]

WordNet (r) 3.0 (2006):

monasticism
    n 1: asceticism as a form of religious life; usually conducted
         in a community under a common rule and characterized by
         celibacy and poverty and obedience

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "monasticism":
   Albigensianism, Catharism, Franciscanism, Sabbatarianism, Trappism,
   Waldensianism, Yoga, abstinence, anchoritic monasticism,
   anchoritism, asceticism, austerity, bachelordom, bachelorhood,
   bachelorism, bachelorship, celibacy, continence, eremitism,
   fasting, flagellation, friarhood, maceration, maidenhead,
   maidenhood, mendicantism, misogamy, misogyny, monachism, monkery,
   mortification, puritanism, rigor, self-denial, self-mortification,
   single blessedness, single state, singleness, spinsterhood,
   unwed state, virgin state, virginity, voluntary poverty