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]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "cumulate":
   accumulate, agglomerate, aggregate, aggroup, amass, assemble,
   backlog, batch, bring together, bulk, bunch, bunch together,
   bunch up, clump, cluster, collect, colligate, collocate, combine,
   compare, compile, conglomerate, corral, dig up, draw together,
   dredge up, drive together, garner, garner up, gather, gather in,
   gather into barns, gather together, get in, get together, group,
   heap up, hide, hive, hoard, hoard up, hold, join, juxtapose, keep,
   lay up, lump together, make up, mass, match, mobilize, muster,
   obtain, pair, partner, pile up, put together, put up, raise,
   rake up, rally, roll up, round up, save, save up, scrape together,
   secrete, secure, squirrel, squirrel away, stock up, stockpile,
   store up, take up, treasure, treasure up, whip in