The Collaborative International Dictionary of English v.0.48:

Shrinkage \Shrink"age\, n.
   1. The act of shrinking; a contraction into less bulk or
      measurement.
      [1913 Webster]

   2. The amount of such contraction; the bulk or dimension lost
      by shrinking, as of grain, castings, etc.
      [1913 Webster]

   3. Decrease in value; depreciation. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

shrinkage
    n 1: process or result of becoming less or smaller; "the
         material lost 2 inches per yard in shrinkage" [syn:
         shrinking, shrinkage]
    2: the amount by which something shrinks
    3: the act of stealing goods that are on display in a store;
       "shrinkage is the retail trade's euphemism for shoplifting"
       [syn: shoplifting, shrinkage]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "shrinkage":
   Sanforizing, ablation, atrophy, attenuation, attrition,
   consumption, corrosion, curtailment, cut, cutting, decrease,
   decrement, deliquescence, depletion, depreciation, derogation,
   detraction, diminution, dip, disparagement, dissipation,
   dissolution, drain, drying, drying up, emaceration, emaciation,
   erosion, evaporation, exhaustion, expenditure, extraction,
   impairment, impoverishment, leakage, lessening, loss, parching,
   preshrinkage, reduction, remission, retraction, retrenchment,
   searing, shortening, shrinking, shriveling, thinning, truncation,
   using, using up, wastage, waste, wasting, wear and tear, wearing,
   wearing away, withering