improvable vs prosperous

improvable

adj
  • Capable of being used to advantage; profitable. 

  • Impossible to prove. 

  • Capable of being improved. 

prosperous

adj
  • Characterized by success. 

  • Well off; affluent. 

  • Favorable. 

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