brittleness vs debility

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. 

debility

noun
  • A state of physical or mental weakness. 

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