notable vs red-letter

notable

adj
  • Worthy of note; remarkable; memorable; noted or distinguished. 

  • Easily noted (without connotations of value); clearly noticeable, conspicuous. 

  • That can be observed; perceptible. 

noun
  • A person or thing of distinction. 

red-letter

adj
  • Particularly significant or positive. 

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