mitigatory vs sedative

mitigatory

adj
  • reducing, lessening the effects of something, generally something painful or uncomfortable 

sedative

adj
  • Calming, soothing, inducing sleep, tranquilizing 

noun
  • An agent or drug that sedates, having a calming or soothing effect, or inducing sleep. 

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