heaped vs impenetrable

heaped

adj

  • Containing a heap. 

  • In a heap. 

impenetrable

adj

  • Not penetrable. 

  • Opaque; obscure; not translucent or transparent. 

  • Incomprehensible; fathomless; inscrutable. 

noun

  • A person not openly given to friendship. 

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