The Collaborative International Dictionary of English v.0.48:

Asceticism \As*cet"i*cism\, n.
   The condition, practice, or mode of life, of ascetics.
   [1913 Webster]

WordNet (r) 3.0 (2006):

asceticism
    n 1: the doctrine that through renunciation of worldly pleasures
         it is possible to achieve a high spiritual or intellectual
         state
    2: the trait of great self-denial (especially refraining from
       worldly pleasures) [syn: austerity, asceticism,
       nonindulgence]
    3: rigorous self-denial and active self-restraint [syn:
       asceticism, ascesis]