safety pin vs swivel

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. 

swivel

noun
  • A piece, such as a ring or hook, attached to another piece by a pin, in such a manner as to permit rotation about the pin as an axis. 

  • A small piece of ordnance, turning on a point or swivel; called also swivel gun. 

  • Strength of mind or character that enables one to overcome adversity; confidence; force of will. 

  • The act of swivelling. 

  • A rotating of the hips. 

  • A small, usually ball- or barrel-shaped device used in angling to connect sections of fishing lines, consisting of two rings linked via a thrust bearing pivot joint. 

verb
  • To swing or turn, as on a pin or pivot. 

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