The Collaborative International Dictionary of English v.0.48:

Americanization \A*mer`i*can*i*za"tion\
   ([.a]*m[~e]r`[i^]*kan*[i^]*z[=a]"sh[u^]n), n.
   The process of Americanizing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Americanization
    n 1: assimilation into American culture [syn: Americanization,
         Americanisation]