collocutor vs interlocutor

collocutor

noun
  • Any of the people engaged in a conversation 

interlocutor

noun
  • A person who takes part in dialogue or conversation. 

  • A man in the middle of the line in a minstrel show who questions the end men and acts as leader. 

  • A decree of a court. 

  • An interlocutory judgement or sentence. 

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