clench vs safety pin

clench

noun
  • A seal that is applied to formed thin-wall bushings. 

  • A tight grip. 

  • A local chapter of the Church of the SubGenius parody religion. 

verb
  • To close tightly. 

  • To grip or hold fast. 

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 clench and safety pin occurred in a corpus of books? (source: Google Ngram Viewer )