Ph.D. vs holder

Ph.D.

noun
  • Doctor of Philosophy, a terminal research degree, the highest of academic degrees conferred by a college or university. 

  • A person who holds a Ph.D. degree. 

holder

noun
  • A thing that holds. 

  • A person who temporarily or permanently possesses something. 

  • The defending champion. 

  • One who is employed in the hold of a vessel. 

How often have the words Ph.D. and holder occurred in a corpus of books? (source: Google Ngram Viewer )