retard vs wind down

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. 

wind down

verb
  • To slow, as if coming to an end; to become calmer or less busy. 

  • To unwind. 

  • To lower by winding, as with a crank or windlass. 

  • To relax; to get rid of stress; to destress. 

  • To shut down slowly (by degrees or in phases). 

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