unavailable vs vain

unavailable

adj
  • Not available. 

noun
  • A communist who operated underground and was therefore not available for a political leadership position. 

vain

adj
  • Having no real substance, value, or importance; empty; void; worthless; unsatisfying. 

  • Overly proud of oneself, especially concerning appearance; having a high opinion of one's own accomplishments with slight reason. 

  • Showy; ostentatious. 

  • Effecting no purpose; pointless, futile. 

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