knag vs safety pin

knag

noun
  • A peg or hook for hanging something on 

  • A pointed rock or crag 

  • A small cask or barrel; a keg or noggin 

  • A knot in a piece of wood or the base of a branch 

  • A short spur or stiff projection from the trunk or branch of a tree, such as the stunted dead branch of a fir 

verb
  • To hang something on a peg 

safety pin

noun
  • A pin in the form of a clasp, which has a guard to cover the sharp point; used to join two pieces of fabric, etc., together temporarily. 

  • The pin of a hand grenade, which prevents accidental detonation. 

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