The Collaborative International Dictionary of English v.0.48:

passivism \pas"si*vism`\ n.
   1. The doctrine that all violence is unjustifiable; hence,
      the principle of passive resistance. [WordNet sense 1]

   Syn: pacifism.
        [WordNet 1.5]

   2. The quality of being passive.
      [PJC]

WordNet (r) 3.0 (2006):

passivism
    n 1: the doctrine that all violence is unjustifiable [syn:
         pacifism, pacificism, passivism]