resistance vs toughness

resistance

noun
  • The act of resisting, or the capacity to resist. 

  • An underground organisation engaged in a struggle for liberation from forceful occupation; a resistance movement. 

  • A force that tends to oppose motion. 

  • electrical resistance. 

toughness

noun
  • Fortitude; hardiness; mettle. 

  • A formidable difficulty. 

  • Resistance to fracture when stressed, or the degree of such resistance. 

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