noun
Specifically the shuttle that holds the bobbin thread in a sewing machine. A technical term used in sewing contexts.
ミシンの下糸入れにボビンをセットしてください。
Please set the bobbin into the shuttle of the sewing machine.
Compound of 下糸 (したい, 'lower thread') and 入れ (いれ, 'container'), literally 'lower-thread container'.