darn - v. - to mend with interlacing stitches; to embroider by filling with long running or interlacing stitches
Wikipedia is a little more descriptive:
Darning is a
sewing technique for repairing holes or worn areas in
fabric or
knitting with needle and thread alone. It is often done by hand, but it is also possible to darn with a
sewing machine. Hand darning employs the darning stitch, a simple
running stitch in which the thread is "woven" in rows along the
grain of the fabric, with the stitcher reversing direction at the end of each row.
Darning also refers to any of several
needlework techniques worked in darning stitches:
Pattern darning is a type of
embroidery that uses
parallel rows of straight stitches of different lengths to create a geometric design.
Net darning, also called
filet lace, is a
19th century technique using stitching on a mesh foundation fabric to imitate
lace.
Needle weaving is a
drawn thread work embroidery technique that involves darning patterns into barelaid warp or weft threads.
This picture didn't teach me anything, so I included it for a laugh. Apparently, this is a picture of "darning." Let me know if you can figure it out.