ad nauseam vs oftentimes

ad nauseam

adv
  • Having been done or repeated so often that it has become annoying or tiresome. 

  • To a nauseating or sickening degree. 

oftentimes

adv
  • (elsewhere, archaic) Frequently; often 

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