exord vs prelims

exord

noun
  • A preface or prefatory passage 

prelims

noun
  • The preliminary front matter of a book, i.e. all content preceding the main text or work itself. 

  • Preliminary examinations taken as a whole, as sat by an individual or year group. 

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