impenetrable vs supple

impenetrable

adj
  • Opaque; obscure; not translucent or transparent. 

  • Not penetrable. 

  • Incomprehensible; fathomless; inscrutable. 

noun
  • A person not openly given to friendship. 

supple

adj
  • Lithe and agile when moving and bending. 

  • Compliant; yielding to the will of others. 

  • Pliant, flexible, easy to bend. 

verb
  • To make or become supple. 

  • To make compliant, submissive, or obedient. 

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