prong vs thorn

prong

verb
  • To pierce or poke with, or as if with, a prong. 

noun
  • A thin, pointed, projecting part, as of an antler or a fork or similar tool. A tine. 

  • The penis. 

  • A branch; a fork. 

thorn

verb
  • To pierce with, or as if with, a thorn (sharp pointed object). 

noun
  • That which pricks or annoys; anything troublesome. 

  • A letter of Latin script (capital: Þ, small: þ), borrowed from the futhark; today used only in Icelandic to represent the voiceless dental fricative, but originally used in several early Germanic scripts, including Old English where it represented the dental fricatives that are today written th (Old English did not have phonemic voicing distinctions for fricatives). 

  • A sharp protective spine of a plant. 

  • Any shrub or small tree that bears thorns, especially a hawthorn. 

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