noun
nail; spike; tack; rivet; brad; pachinko pin
General term for a metal fastener with a pointed end, used in construction, carpentry, and also for pachinko machine pins.
壁に釘を打って絵を掛けた。
I hammered a nail into the wall and hung a picture.
パチンコ台の釘が曲がっている。
The pins on the pachinko machine are bent.
The kanji 釘 is a phono-semantic compound with 金 (metal) and 丁 (nail-shaped). The reading くぎ is native Japanese.