decisive vs irrevocable

decisive

adj
  • Having the power or quality of deciding a question or controversy; putting an end to contest or controversy; final; conclusive. 

  • Marked by promptness and decision. 

irrevocable

adj
  • Unable to be retracted or reversed; final. 

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