amass vs cumulate

amass

verb
  • to gather a great quantity of; to accumulate. 

  • To accumulate; to assemble. 

  • To collect into a mass or heap. 

cumulate

verb
  • To be accumulated. 

  • To accumulate; to amass. 

noun
  • An igneous rock formed by the accumulation of crystals from a magma either by settling or floating. 

adj
  • accumulated, agglomerated, amassed 

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