grinding vs strengthening

grinding

noun
  • The action of grinding together or crushing into small particles. 

  • A form of dance in which two people rub their bodies together. 

  • Repeatedly performing the same quest or similar in-game activity in order to amass points or wealth. 

adj
  • Relentlessly taxing; burdensome; exacting to the point of exhaustion. 

  • Of or pertaining to the act or sound of grinding. 

strengthening

noun
  • The process by which something is strengthened. 

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