catacomb vs ossuary

catacomb

noun
  • An underground system of tunnels and chambers with recesses for graves, used (in former times) as a cemetery; a tunnel system used for burying the dead, as in Paris or Ancient Rome. 

ossuary

noun
  • A container, receptacle, or building, such as an urn or vault, for holding the bones of the dead. 

How often have the words catacomb and ossuary occurred in a corpus of books? (source: Google Ngram Viewer )