catacomb vs crypt

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. 

crypt

noun
  • An underground vault, especially one beneath a church that is used as a burial place. 

  • Any of the genus Cryptopus of orchids of Madagascar and Mauritius. 

  • A small pit or cavity in the surface of an organ or other structure. 

  • Any of the genus Cryptocoryne of aquatic plants of southern and southeastern Asia. 

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