The Collaborative International Dictionary of English v.0.48:

nationalisation \nationalisation\ n.
   same as nationalization. [Chiefly Brit.]
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

nationalisation
    n 1: the action of forming or becoming a nation [syn:
         nationalization, nationalisation]
    2: the action of rendering national in character [syn:
       nationalization, nationalisation]
    3: changing something from private to state ownership or control
       [syn: nationalization, nationalisation, communization,
       communisation] [ant: denationalisation,
       denationalization, privatisation, privatization]