doubt vs security

doubt

verb
  • To be undecided about; to lack confidence in; to disbelieve, to question. 

noun
  • Disbelief or uncertainty (about something); (countable) a particular instance of such disbelief or uncertainty. 

security

noun
  • Proof of ownership of stocks, bonds or other investment instruments. 

  • Property etc. temporarily relinquished to guarantee repayment of a loan. 

  • Something that secures the fulfillment of an obligation or law. 

  • A guarantee. 

  • The condition of not being threatened, especially physically, psychologically, emotionally, or financially. 

  • Something that secures. 

  • An organization or department responsible for providing security by enforcing laws, rules, and regulations as well as maintaining order. 

  • Freedom from apprehension. 

  • A tradeable financial asset, such as a share of stock.ᵂ 

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