anterior vs introductory

anterior

adj
  • Coming before or earlier in time or development, prior to, preceding. 

  • Pronounced with an obstruction located in front of the palato-alveolar region of the mouth, e.g. b, p, d, t. 

  • (of a part of a flower or leaf) Situated further away from the mainstem. 

  • Nearer the forward end, especially in the front of the body; nearer the head or forepart of an animal. 

introductory

adj
  • Introducing; giving a preview or idea of. 

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