impenetrable vs inimic

impenetrable

adj

  • Incomprehensible; fathomless; inscrutable. 

  • Opaque; obscure; not translucent or transparent. 

  • Not penetrable. 

noun

  • A person not openly given to friendship. 

inimic

adj

  • Inimical. 

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