relentless vs yielding

relentless

adj

  • Unrelenting or unyielding in severity. 

  • Unremitting, steady and persistent. 

yielding

adj

  • Docile, or inclined to give way to pressure. 

noun

  • A concession. 

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