catchword vs polyword

catchword

noun
  • A word or expression repeated until it becomes representative of a party, school, business, or point of view. 

  • The last word of a speech, serving as a cue for the next speaker. 

  • A word under the right-hand side of the last line on a book page that repeats the first word on the following page. 

polyword

noun
  • A phrase that acts like a single word. 

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