invite vs strengthen

invite

verb
  • To encourage. 

  • To ask for the presence or participation of someone or something. 

  • To allure; to draw to; to tempt to come; to induce by pleasure or hope; to attract. 

  • To request formally. 

noun
  • An invitation. 

strengthen

verb
  • To reinforce, to add to, to support (someone or something) 

  • To make strong or stronger; to add strength to; to increase the strength of; to fortify. 

  • To empower; to give moral strength to; to encourage; to enhearten. 

  • To grow strong or stronger. 

  • To substantiate; to corroborate (a belief, argument, etc.) 

  • To augment; to improve; to intensify. 

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