unhappy vs vital

unhappy

noun
  • An individual who is not happy. 

adj
  • Not happy; sad. 

  • Not satisfied; unsatisfied. 

vital

adj
  • Invigorating or life-giving. 

  • Very important. 

  • Containing life; living. 

  • Necessary to continued existence. 

  • Necessary to the continuation of life; being the seat of life; being that on which life depends. 

  • Capable of living; in a state to live; viable. 

  • Relating to the recording of life events. 

  • Relating to, or characteristic of life. 

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