fortify vs weaken

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. 

weaken

verb
  • To make weaker or less strong. 

  • To become weaker or less strong. 

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