eburnation
  骨質象牙化
  eb·ur·na·tion /ˌɛbɝˈneʃən, ˌɪbɝ-/ 名詞
  骨質象牙化,骨質緻密
  E·bur·na·tion n.  Med. A condition of bone cartilage occurring in certain diseases of these tissues, in which they acquire an unnatural density, and come to resemble ivory.
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  eburnation
       n : a change that occurs in degenerative joint disease in which
           bone is converted into a dense smooth substance
           resembling ivory