thread knot; knot at the end of a thread
A small knot tied at the end of a sewing thread to prevent it from slipping through the fabric. Common in hand-sewing contexts.
After threading the needle, first make a knot at the end of the thread.
Compound of 玉 (tama, 'ball, bead') and 結び (musubi, 'knot'), referring to the small round shape of the knot.