detain vs retard

detain

verb
  • To keep back or from; to withhold. 

  • To put under custody. 

  • To seize goods for official purposes. 

  • To keep someone from proceeding by holding them back or making claims on their attention. 

retard

verb
  • To put off; to postpone. 

  • To decelerate; to slow down. 

  • 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 detain and retard occurred in a corpus of books? (source: Google Ngram Viewer )