brittleness vs sickliness

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. 

sickliness

noun
  • The state or characteristic of weakness, incapacity, or physical distress due to poor health, especially of a chronic nature. 

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