noun
ornamental clip; decorative clasp
Refers to a small decorative clip used to fasten hair, obi sashes, or other accessories. The name is onomatopoeic from the snapping sound it makes.
浴衣の帯にぱちん留めをつける。
I attach an ornamental clip to the obi of my yukata.
髪に小さなぱちん留めをして、前髪をとめた。
I used a small ornamental clip to hold back my bangs.
ヘアピン is a hairpin, usually a simple U-shaped pin, whereas ぱちん留め is a clip with a clasp mechanism.
From the onomatopoeia ぱちん (snap) and 留め (fastener), referring to the snapping sound the clip makes when closed.