constantly vs interminably

constantly

adv
  • In a constant manner; occurring continuously; persistently. 

  • In an unchangeable or invariable manner; in every case. 

  • Recurring regularly. 

interminably

adv
  • in an interminable manner; (seemingly) endlessly 

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