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.
上糸 is the upper thread, contrasting with 下糸 (lower thread) which is housed in the 下糸入れ.
Compound of 下糸 (したい, 'lower thread') and 入れ (いれ, 'container'), literally 'lower-thread container'.