outstanding vs red-letter

outstanding

adj
  • Exceptionally good; distinguished from others by its superiority. 

  • Projecting outwards. 

  • Prominent or noticeable; standing out from others. 

  • Unresolved; not settled or finished. 

  • Owed as a debt. 

red-letter

adj
  • Particularly significant or positive. 

How often have the words outstanding and red-letter occurred in a corpus of books? (source: Google Ngram Viewer )