communion vs rogation

communion

noun
  • Holy Communion. 

  • A form of ecclesiastical unity between the Roman Church and another, so that the latter is considered part of the former. 

  • A joining together of minds or spirits; a mental connection. 

rogation

noun
  • A deeply serious and somber prayer or entreaty. 

  • The demand, by the consuls or tribunes, of a law to be passed by the people; a proposed law or decree. 

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