crypt vs ostium

crypt

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

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

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

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

ostium

noun
  • A small opening or orifice, as in a body organ or passage. 

  • Any of the small openings or pores in a sponge. 

  • The mouth of a river. 

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