reassurance vs uncertainty

reassurance

noun
  • The act of confirming someone's opinion or impression. 

  • Reinsurance. 

  • The feeling of being reassured, of having confidence restored, of having apprehensions dispelled. 

uncertainty

noun
  • Doubt; the condition of being uncertain or without conviction. 

  • A parameter that measures the dispersion of a range of measured values. 

  • Something uncertain or ambiguous. 

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