retard vs rev 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. 

rev up

verb
  • To increase the speed of an engine, especially that of a stationary motor car. 

  • To become more active. 

  • To make (someone or something) more active. 

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