noun
blind stitch
A sewing technique where stitches are hidden inside the hem or seam, used for finishing edges neatly.
スカートの裾を絎縫いで仕上げる。
Finish the hem of the skirt with a blind stitch.
まつり縫い is a similar hemming stitch but often refers to a visible slipstitch, while 絎縫い specifically hides the stitches.
Compound of 絎 (kuke, 'blind stitching') + 縫い (nui, 'sewing'). The exact origin of 絎 is uncertain, but it is a specialized sewing kanji.