downshift vs retard

downshift

verb
  • To function at a lower rate; to slacken. 

  • To reduce (something) in quality or quantity (as effect, scope, speed, etc.) 

  • To shift a transmission into a lower gear. 

  • To shift (a car or bicycle) into a lower gear. 

  • To change (one's career or lifestyle) to one which is not as well paid but less stressful and more personally rewarding. 

  • To change one's career or lifestyle to one which is not as well paid but less stressful and more personally rewarding. 

noun
  • A change in career or lifestyle to one which is not as well paid but less stressful and more personally rewarding. 

  • A shift of a transmission into a lower gear. 

  • A change of direction or a movement downwards. 

  • A reduction in quality or quantity. 

retard

verb
  • To decelerate; to slow down. 

  • To put off; to postpone. 

  • To keep delaying; to continue to hinder; to prevent from progressing. 

noun
  • Retardation; delay. 

  • A slowing down of the tempo; a ritardando. 

  • A person or being who is extremely stupid or slow to learn. 

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