tumulus

from WordNet (r) 3.0 (2006)

tumulus
    n 1: (archeology) a heap of earth placed over prehistoric tombs
         [syn: {burial mound}, {grave mound}, {barrow}, {tumulus}]

from The Collaborative International Dictionary of English v.0.48

Tumulus \Tu"mu*lus\, n.; pl. {Tumuli}. [L., a mound, a
   sepulchral mound, probably from tumere to swell. Cf.
   {Tumid}.]
   An artificial hillock, especially one raised over a grave,
   particularly over the graves of persons buried in ancient
   times; a barrow.
   [1913 Webster]