The Collaborative International Dictionary of English v.0.48:

Cumulate \Cu"mu*late\ (k?"m?-l?t), v. t. [imp. & p. p.
   Cumulated (-l?`t?d); p. pr. & vb. n. Cumulating
   (-l?`t?ng).] [L. cumulatus, p. p. of cumulare to heap up, fr.
   cumulus a heap. See Cumber.]
   To gather or throw into a heap; to heap together; to
   accumulate.
   [1913 Webster]

         Shoals of shells, bedded and cumulated heap upon heap.
                                                  --Woodward.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cumulate
    v 1: collect or gather; "Journals are accumulating in my
         office"; "The work keeps piling up" [syn: accumulate,
         cumulate, conglomerate, pile up, gather, amass]