leech vs medical doctor

leech

noun
  • A healer. 

  • A person who derives profit from others in a parasitic fashion. 

  • The aft edge of a triangular sail. 

  • An aquatic blood-sucking annelid of class Hirudinea, especially Hirudo medicinalis. 

  • The vertical edge of a square sail. 

verb
  • To drain (resources) without giving back. 

  • To apply a leech medicinally, so that it sucks blood from the patient. 

medical doctor

noun
  • A physician; a person who holds a doctoral degree or first professional degree in medicine, and practices in that profession. 

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