uncertain vs unsure

uncertain

adj
  • Not certain; unsure. 

  • Not yet determined; undecided. 

  • Variable and subject to change. 

  • Fitful or unsteady. 

  • Unpredictable or capricious. 

  • Not known for certain; questionable. 

noun
  • Something uncertain. 

unsure

adj
  • uncertain 

  • unstable or precarious 

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