The Collaborative International Dictionary of English v.0.48:

Polymerization \Pol`y*mer`i*za"tion\, n. (Chem.)
   The act or process of changing to a polymeric form; the
   condition resulting from such change.
   [1913 Webster]

WordNet (r) 3.0 (2006):

polymerization
    n 1: a chemical process that combines several monomers to form a
         polymer or polymeric compound [syn: polymerization,
         polymerisation]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "polymerization":
   acetification, acidification, acidulation, alkalization,
   carbonation, catalysis, chemicalization, electrolysis, ferment,
   fermentation, hydrogenation, isomerism, metamerism, metamerization,
   nitration, oxidation, oxidization, phosphatization, polymerism,
   position isomerism, reduction, saturization, working