incentive vs tranquilizer

incentive

adj
  • Inciting; encouraging or moving; rousing to action; stimulating. 

  • Serving to kindle or set on fire. 

noun
  • Something that motivates, rouses, or encourages. 

  • A bonus or reward, often monetary, to work harder. 

tranquilizer

noun
  • That which tranquillizes or soothes. 

  • A drug used to reduce anxiety or tension. 

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