doubtless vs incontrovertibly

doubtless

adv
  • Without doubt; very probably, in all likelihood; doubtlessly. 

adj
  • Characterized by or experiencing no doubt at all, certain; undoubted; undoubting. 

incontrovertibly

adv
  • In an incontrovertible manner; in a manner not capable of being denied, challenged, or disputed. 

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