exterior vs subsurface

exterior

noun
  • The outside part, parts or surface of something. 

  • Foreign lands. 

adj
  • Being from outside a country; foreign. 

  • Outdoor. 

  • Relating to the outside parts or surface of something. 

subsurface

noun
  • Something that is below the layer that is on the surface. 

  • A surface which is a submanifold of another surface. 

adj
  • below the surface 

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