The Collaborative International Dictionary of English v.0.48:

immobilisation \immobilisation\ immobilization
\immobilization\n.
   The act or process of limiting movement or making incapable
   of movement; as, immobilization of the injured knee was
   necessary; the storm caused complete immobilization of the
   rescue team.

   Syn: immobilizing.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

immobilization
    n 1: fixation (as by a plaster cast) of a body part in order to
         promote proper healing; "immobilization of the injured knee
         was necessary" [syn: immobilization, immobilisation]
    2: the act of limiting movement or making incapable of movement;
       "the storm caused complete immobilization of the rescue team"
       [syn: immobilization, immobilisation, immobilizing]