ofttimes vs once

ofttimes

adv
  • (elsewhere, archaic) often, frequently 

once

conj
  • As soon as; when; after. 

adv
  • Multiplied by one: indicating that a number is multiplied by one. 

  • One and only one time. 

  • Formerly; during some period in the past. 

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