fortify vs retard

fortify

verb
  • To impart strength or vigor to. 

  • To increase the nutritional value of food by adding ingredients. 

  • To increase the defenses of; to strengthen and secure by military works; to render defensible against an attack by hostile forces. 

  • To add spirits to wine to increase the alcohol content. 

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