The Collaborative International Dictionary of English v.0.48:

Colonization \Col`o*ni*za"tion\, n. [Cf. F. colonisation.]
   The act of colonizing, or the state of being colonized; the
   formation of a colony or colonies.
   [1913 Webster]

         The wide continent of America invited colonization.
                                                  --Bancroft.
   [1913 Webster]

WordNet (r) 3.0 (2006):

colonization
    n 1: the act of colonizing; the establishment of colonies; "the
         British colonization of America" [syn: colonization,
         colonisation, settlement]