The Collaborative International Dictionary of English v.0.48:

Stratification \Strat`i*fi*ca"tion\, n. [Cf. F. stratification.]
   1. The act or process of laying in strata, or the state of
      being laid in the form of strata, or layers.
      [1913 Webster]

   2. (Physiol.) The deposition of material in successive layers
      in the growth of a cell wall, thus giving rise to a
      stratified appearance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stratification
    n 1: the act or process or arranging persons into classes or
         social strata
    2: the condition of being arranged in social strata or classes
       within a group [syn: stratification, social
       stratification]
    3: forming or depositing in layers
    4: a layered configuration
    5: the placing of seeds in damp sand or sawdust or peat moss in
       order to preserve them or promote germination

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "stratification":
   analysis, arrangement, cataloging, categorization, classification,
   codification, delamination, desquamation, division, exfoliation,
   filing, flakiness, foliation, furfuration, grading, grouping,
   indexing, lamellation, lamination, pigeonholing, placement,
   ranging, ranking, rating, scaliness, sorting, subdivision,
   tabulation, taxonomy, typology