prosaicism vs shibboleth

prosaicism

noun
  • The quality or state of being prosaic; a prosaic manner or style. 

shibboleth

noun
  • A common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth. 

  • A particular pronunciation or custom that is regarded as distinguishing members of a group from non-members, especially when used as a test. 

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