retro vs retrogressive

retro

adj
  • Affecting things past; retroactive, ex post facto. 

  • Of, or relating to, the past, past times, or the way things were. 

noun
  • Past fashions or trends. 

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. 

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