accumulationEnglishOxford American Thesaurusaccumulation noun 1 the accumulation of money: amassing, building up, buildup, collection, gathering, assembling, assembly, stockpiling, hoarding, cumulation, accrual; rare amassment. ▷antonyms dissipation. 2 an accumulation of garbage: mass, buildup, pile, heap, stack, collection, gathering, stock, store, stockpile, reserve, hoard, bank, pool, fund, mine, reservoir, cumulation, accrual, aggregation, accretion, agglomerate, agglomeration.