free rider vs leech

free rider

noun
  • One who obtains benefit from a public good without paying for it directly. 

  • A worker at an open shop who is able to enjoy the benefits negotiated by a union without being a member of the union. 

  • Someone who obtains goods or services legally without paying. 

leech

noun
  • 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. 

  • A healer. 

  • 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. 

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