disculpate vs exonerate

disculpate

verb
  • To free from blame or the imputation of a fault; to exonerate. 

exonerate

verb
  • To free (someone) from accusation or blame. 

  • To free (someone) from an obligation, responsibility or task. 

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