Refers to the line of stitching or the individual stitch in sewing.
The stitches were crooked, so I unpicked them and redid them.
Set the sewing machine to a fine stitch length.
Compound of 針 (hari, 'needle') and 目 (me, 'eye' or 'mark'), referring to the mark or hole made by a needle, i.e., a stitch.