headstrong vs obdurate

headstrong

adj
  • Determined to do as one pleases, and not as others want. 

obdurate

adj
  • Hardened against feeling; hard-hearted. 

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

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