retardate vs wind down

retardate

noun
  • A retarded person; a person with retardation. 

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 retardate and wind down occurred in a corpus of books? (source: Google Ngram Viewer )