buy vs invalidate

buy

verb
  • to accept as true; to believe 

  • To make a purchase or purchases, to treat (for a drink, meal or gift) 

  • To make a bluff, usually a large one. 

  • To bribe. 

  • To be equivalent to in value. 

  • To obtain (something) in exchange for money or goods. 

  • To obtain, especially by some sacrifice. 

noun
  • Something which is bought; a purchase. 

invalidate

verb
  • To make or declare (an argument, statement, or theory) unsound or erroneous; disprove. 

  • To make invalid. Especially applied to contract law. 

  • To render invalid; discredit. 

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