backstab vs castigate

backstab

verb
  • to attack someone (especially verbally) unfairly in a deceitful, underhand, or treacherous manner, especially when they're not present in the place or situation that it happens. (as if stabbing them in the back). See backbite. 

castigate

verb
  • To punish or reprimand someone severely. 

  • To revise or make corrections to a publication. 

  • To execrate or condemn something in a harsh manner, especially by public criticism. 

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