lenient vs relentless

lenient

noun

  • A lenitive; an emollient. 

adj

  • Lax; not strict; tolerant of dissent or deviation 

relentless

adj

  • Unrelenting or unyielding in severity. 

  • Unremitting, steady and persistent. 

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