reel for a spare bowstring
Specialized term for a traditional archery accessory: a small reel or spool used to hold a spare bowstring, typically carried by a kyūdō practitioner.
As part of kyūdō equipment, a spare bowstring is wound onto a tsurumaki.
Compound of 弦 (tsuru, 'bowstring') and 巻 (maki, 'winding' or 'reel'). The exact historical derivation is uncertain, but the word transparently describes its function.