slogging vs tireless

slogging

noun
  • An act or an instance of slogging or working laboriously. 

  • A beating or thrashing. 

tireless

adj
  • Indefatigable, untiring and not yielding to fatigue 

  • Without a tire (wheel covering); tyreless. 

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