brittleness vs infirmity

brittleness

noun
  • The state of being brittle; aptness to break; fragility. 

  • The property by virtue of which a material is fractured without appreciable deformation by the application of load. 

infirmity

noun
  • a moral weakness or defect 

  • feebleness, frailty or ailment, especially due to old age. 

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