accumulate vs upheap

accumulate

verb
  • To heap up in a mass; to pile up; to collect or bring together (either literally or figuratively) 

  • To gradually grow or increase in quantity or number. 

adj
  • Collected; accumulated. 

upheap

verb
  • To pile or heap up; accumulate. 

How often have the words accumulate and upheap occurred in a corpus of books? (source: Google Ngram Viewer )