retrogressive vs worsen

retrogressive

adj
  • Of or relating to retrogression. 

  • Directed towards the rear or the past; retrograde. 

noun
  • A person of retrogressive views or policies; a backward-looking conservative. 

worsen

verb
  • To make worse; to impair. 

  • To become worse; to get worse. 

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