continuative vs relentless

continuative

adj
  • Of or pertaining to continuation. 

  • durative. 

noun
  • a durative. 

  • Something that causes a continuation. 

relentless

adj
  • Unremitting, steady and persistent. 

  • Unrelenting or unyielding in severity. 

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