middle school vs phrontistery

middle school

noun
  • A school which crosses the traditional divide between primary school and secondary school. 

  • An educational level or stage between primary school and secondary school. 

phrontistery

noun
  • An establishment devoted to education or study. 

  • A place for thinking. 

  • The toilet; the lavatory. 

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