disrupt vs retard

disrupt

verb
  • To interrupt or impede. 

  • To throw into confusion or disorder. 

  • To improve a product or service in ways that displace an established one and surprise the market. 

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