degeneration vs disuse

degeneration

noun
  • The process or state of growing worse, or the state of having become worse. 

  • That condition of a tissue or an organ in which its vitality has become either diminished or perverted; a substitution of a lower for a higher form of structure. 

  • Gradual deterioration, from natural causes, of any class of animals or plants or any particular organ or organs; hereditary degradation of type. 

  • A thing that has degenerated. 

disuse

noun
  • The state of not being used; neglect. 

verb
  • To cease the use of. 

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