backbone vs idleness

backbone

noun
  • Courage, fortitude, or strength. 

  • The series of vertebrae, separated by disks, that encloses and protects the spinal cord, and runs down the middle of the back in vertebrate animals. 

  • Any fundamental support, structure, or infrastructure. 

idleness

noun
  • Groundlessness; worthlessness; triviality; vanity; frivolity. 

  • The state of being idle; inactivity. 

  • The state of being indolent; indolence. 

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