pterygium vs pushpin

pterygium

noun
  • A generalized limb of a vertebrate 

  • An abnormal mass of tissue in the corner of the eye that obstructs vision 

pushpin

noun
  • A thumbtack, especially one with a cylindrical head. 

verb
  • To fasten with a thumbtack. 

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