let off vs ostracize

let off

verb
  • To forgive and not punish. 

  • To cause to explode or come out; to release. 

ostracize

verb
  • To exclude a person from a community or from society by not communicating with them or by refusing to acknowledge their presence; to refuse to associate with or talk to; to shun. 

  • To ban a person from a city for five or ten years through the procedure of ostracism. 

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