pushpin; thumbtack; drawing pin
A small pin with a flat head, pushed into a surface to attach paper or light items. It is Kansai dialect, but it is widely understood.
See also: 画鋲
I pinned the calendar to the wall with a pushpin.
We're out of pushpins, so please buy some.
Compound of 押し (oshi, 'push') and ピン (pin, from English 'pin').