for sure vs undeniably

for sure

prep
  • definitely, positively, without doubt 

undeniably

adv
  • Used as a modal adverb to assert that that the indicated statement is undeniable. 

  • In an undeniable manner, or to an undeniable extent. 

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