Source : Webster's Revised Unabridged Dictionary (1913)

Stratify \Strat"i*fy\, v. t. [imp. & p. p. {Stratified}; p. pr.
   & vb. n. {Stratifying}.] [Stratum + -fy: cf. F. stratifier.]
   To form or deposit in strata, or layers, as substances in the
   earth; to arrange in strata.

Source : WordNet®

stratify
     v 1: divide society into social classes or castes; "Income
          distribution often stratifies a society"
     2: form layers or strata; "The rock stratifies"
     3: develop different social levels, classes, or castes;
        "Society stratifies when the income gap widens"
     4: form, arrange, or deposit in layers; "The fish are
        stratified in barrels"; "The rock was stratified by the
        force of the water"; "A statistician stratifies the list
        of names according to the addresses"
     5: render fertile and preserve by placing between layers of
        earth or sand; "stratify seeds"
     [also: {stratified}]