hymen vs pleura

hymen

noun
  • A membrane which completely or partially occludes the vaginal opening in human females. 

  • Marriage. 

pleura

noun
  • Each of a pair of smooth serous membranes which line the thorax and envelop the lungs in humans and other mammals. 

  • A lateral part in an animal body or structure. 

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