[1] : The Collaborative International Dictionary of English v.0.48

tumulus \tu"mulus\, 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
see also:
tumuli tumid 

[2] : WordNet (r) 2.0

tumulus
     n : archeology a heap of earth placed over prehistoric tombs
         syn: burial mound, grave mound, barrow
see also:
burial mound grave mound barrow 

Tumulus >> T Words
Tumulus, definition of term: Tumulus
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