introduce vs nullify

introduce

verb
  • To bring (something) into practice. 

  • To cause (someone) to be acquainted (with someone else). 

  • To add (something) to a system, a mixture, or a container. 

  • To make (something or someone) known by formal announcement or recommendation. 

nullify

verb
  • To prevent from happening. 

  • To make of no use or value; to cancel out. 

  • To make legally invalid. 

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