The Collaborative International Dictionary of English v.0.48:

miniaturization \miniaturization\ n.
   The act or process of making on a greatly reduced scale.

   Syn: miniaturisation.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

miniaturization
    n 1: act of making on a greatly reduced scale [syn:
         miniaturization, miniaturisation]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "miniaturization":
   abatement, abridgment, alleviation, attenuation, contraction,
   dampening, damping, decrease, decrement, decrescence, deduction,
   deflation, depreciation, depression, diminishment, diminution,
   dying, dying off, extenuation, fade-out, languishment, lessening,
   letup, lowering, mitigation, reduction, relaxation, sagging,
   scaling down, simplicity, subtraction, weakening