Cotter pin

Cotter pin can mean:

• In USA usage:
  • A split pin, a metal fastener with two tines that are bent during installation used to fasten metal together, like with a staple or rivet
  • Hairpin cotter pin, more commonly known as an "R-clip"
  • Bowtie cotter pin, a vibration-proof type of R-clip that is shaped like a bowtie
  • Circle cotter, a ring-shaped cotter pin
• In British usage:
  • A cotter, in mechanical engineering a pin or wedge passing through a hole to fix parts tightly together

This usage difference is often a cause of confusion when companies of both countries work together.