apothegm vs headword

apothegm

noun
  • A short, witty, instructive saying; an aphorism or maxim. 

headword

noun
  • Any word which may be modified by an adjunct. 

  • A word used as the title of a section, particularly in a dictionary, encyclopedia, or thesaurus. 

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