Definitions for "headpin"
A wire finding with a stop at the end of it - use to thread on beads or other findings to make dangles, earrings, etc etc.
a straight piece of wire with a flat head at one end
a straight piece of wire with watch clasp a flat head at
The front pin in the triangular arrangement of ten pins.
The number one pin.
The front pin or the 1-pin on the rack. Also called kingpin.