hydrophobia vs instability

hydrophobia

noun
  • An aversion to water, as a symptom of rabies; the disease of rabies itself. 

  • A morbid fear of water; aquaphobia. 

instability

noun
  • The quality of being unstable. 

  • A state that is not in equilibrium, or in which a small change has a large irreversible effect. 

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