tumulus
noun /ˈtjuːmjələs/
  /ˈtuːmjələs/
(plural tumuli 
 (specialist) /ˈtjuːmjəlaɪ/
  /ˈtuːmjəlaɪ/
)- a large pile of earth built over the grave of an important person in ancient timesWord Originlate Middle English: from Latin; related to tumere ‘swell’.