retard vs warm up

retard

noun
  • Retardation; delay. 

  • A slowing down of the tempo; a ritardando. 

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

verb
  • To put off; to postpone. 

  • To decelerate; to slow down. 

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

warm up

verb
  • To reach, or cause to reach, a normal operating temperature (of a car for example). 

  • To become warmer. 

  • To heat or reheat (e.g. food). 

  • To do gentle exercise, stretching etc., in order to prepare the body for more vigorous exercise. 

  • To make (an audience) enthusiastic or animated before a show 

  • To prepare for an activity by carrying out a practice or preparation routine. 

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