sarcasm vs sardonicism

sarcasm

noun
  • An act of sarcasm. 

  • Use of acerbic language to mock or convey contempt, often using irony and (in speech) often marked by overemphasis and a sneering tone of voice. 

sardonicism

noun
  • The quality of being sardonic 

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