red-letter vs sorry

red-letter

adj
  • Particularly significant or positive. 

sorry

noun
  • The act of saying sorry; an apology. 

intj
  • Expresses regret, remorse, or sorrow. 

  • Used as a request for someone to repeat something not heard or understood clearly. 

  • Said as a request to pass somebody. 

  • Used to correct oneself in speech. 

adj
  • Grieved or saddened, especially by the loss of something or someone. 

  • Pathetic; contemptibly inadequate. 

  • Poor, pitifully sad or regrettable. 

  • Regretful or apologetic for one's actions. 

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