The Collaborative International Dictionary of English v.0.48:

Nationalization \Na`tion*al*i*za"tion\, n.
   The act of nationalizing, or the state of being nationalized.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nationalization
    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]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "nationalization":
   Americanization, Fabian socialism, Fabianism, Marxian socialism,
   Marxism, Saint-Simonism, acculturation, admission, adoption,
   affiliation, angary, annexation, annexure, assimilation,
   attachment, citizenship by naturalization, citizenship papers,
   collective ownership, collectivism, collectivization,
   commandeering, communalization, communization, confiscation,
   culture shock, distraint, distress, eminent domain, execution,
   expropriation, garnishment, guild socialism, impoundment,
   impressment, levy, naturalization, naturalized citizenship, papers,
   phalansterism, public ownership, right of angary, sequestration,
   socialism, socialization, state socialism, utopian socialism