sapping vs tiring

sapping

noun
  • The act by which something is sapped or depleted. 

  • The act of excavating trenches. 

  • The act of being struck with a sap or club. 

tiring

noun
  • The action of tiring. 

  • Bits of bone and tough organic material from a corpse given to hawks to abate their hunger. 

adj
  • That tires or tire. 

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