accumulate (v.) Look up accumulate at Dictionary.com
1520s, "to heap up" (transitive), from Latin accumulatus, past participle of accumulare "to heap up, amass," from ad "to," here perhaps emphatic (see ad-), + cumulare "heap up," from cumulus "heap" (see cumulus). From 1759 in intransitive sense of "grow in size or number." Related: Accumulated; accumulating.