hyperkinesis vs indeclinability

hyperkinesis

noun
  • A condition especially of childhood characterized by hyperactivity. 

  • Abnormally increased and sometimes uncontrollable activity or muscular movements. 

indeclinability

noun
  • The quality of being indeclinable. 

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