comeback vs improvement

comeback

noun
  • A retort or answer, particularly a quick or clever one. 

  • A return (e.g. to popularity, success, etc.) after an extended period of obscurity. 

  • An occurrence of an athlete or sports team in a competition overcoming a substantial disadvantage in points to win or draw. 

improvement

noun
  • A useful addition to, or modification of, a machine, manufacture, or composition. 

  • Increase; growth; progress; advance. 

  • The act of improving; advancement or growth; a bettering 

  • Something which is improved 

  • Valuable additions or betterments, for example buildings, clearings, drains, fences, etc., on premises. 

  • The state of being improved; betterment; advance 

  • The act of making profitable use or application of anything, or the state of being profitably employed; practical application, for example of a doctrine, principle, or theory, stated in a discourse. 

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