The Collaborative International Dictionary of English v.0.48:

Charnel \Char"nel\, a. [F. charnel carnal, fleshly, fr. L.
   carnalis. See Carnal.]
   Containing the bodies of the dead. "Charnel vaults."
   --Milton.
   [1913 Webster]

   Charnel house, a tomb, vault, cemetery, or other place
      where the bones of the dead are deposited; originally, a
      place for the bones thrown up when digging new graves in
      old burial grounds.
      [1913 Webster]

WordNet (r) 3.0 (2006):

charnel house
    n 1: a vault or building where corpses or bones are deposited
         [syn: charnel house, charnel]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "charnel house":
   barrow, beehive tomb, bone house, box grave, burial,
   burial chamber, burial mound, burning ghat, catacombs, cenotaph,
   cist, cist grave, crematorium, crematory, cromlech, crypt,
   deadhouse, deep six, dokhma, dolmen, grave, house of death,
   last home, long home, low green tent, low house, mastaba,
   mausoleum, monstrance, morgue, mortuary, mummy chamber,
   narrow house, ossuarium, ossuary, passage grave, pit, pyramid,
   reliquary, resting place, sepulcher, shaft grave, shrine, stupa,
   tomb, tope, tower of silence, tumulus, vault