impairment vs unsadness

impairment

noun
  • A deterioration or weakening 

  • The result of being impaired 

  • A downward revaluation, a write-down. 

  • A disability or handicap 

  • an inefficient part or factor. 

unsadness

noun
  • infirmity, unsteadiness, weakness 

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