put the brakes on vs retard

put the brakes on

verb
  • To stop (an event, action, or process) or to slow it down. 

  • To cease to perform one's current activity or to decrease one's level of activity. 

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 put the brakes on and retard occurred in a corpus of books? (source: Google Ngram Viewer )