cloaca vs necessarium

cloaca

noun
  • An outhouse or lavatory. 

  • A sewer. 

  • A duct through which gangrenous material escapes a body. 

  • The duct in reptiles, amphibians and birds, as well as most fish and some mammals, which serves as the common outlet for urination, defecation, and reproduction. 

necessarium

noun
  • A lavatory. 

  • Synonym of reredorter: a monastery's latrine, outhouse, or lavatory, typically located behind the dormitory. 

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