obdurate vs struggleful

obdurate

adj
  • Hardened against feeling; hard-hearted. 

  • Stubbornly persistent, generally in wrongdoing; refusing to reform or repent. 

struggleful

adj
  • Full of struggle; difficult, hard. 

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