noun
thimble
A small cap worn on the finger to push a needle when sewing.
裁縫をするときは、指貫を中指にはめます。
When sewing, I put a thimble on my middle finger.
Compound of 指 (yubi, 'finger') and 貫き (nuki, 'piercing' or 'passing through'), from the verb 貫く (tsuranuku). The spelling 指貫 is a straightforward representation of the meaning.