let-off vs punishment

let-off

noun
  • An escape from punishment. 

  • A device for letting off, releasing, or giving forth, as the warp from the cylinder of a loom. 

punishment

noun
  • A suffering by pain or loss imposed as retribution 

  • A penalty to punish wrongdoing, especially for crime. 

  • Any harsh treatment or experience; rough handling. 

  • The act or process of punishing, imposing and/or applying a sanction. 

How often have the words let-off and punishment occurred in a corpus of books? (source: Google Ngram Viewer )