Sentence:  You can sew a <WSD>godet</WSD> into a slit cut perpendicular to a hem edge, but it's more common—and much easier—to insert it into a vertical panel seam, as shown here. Because <WSD>godets</WSD> are shaped pieces, often with a pronounced curve at the hem edge, they can be tricky to hem. 
Meaning of the word marked with <WSD> tags:  A piece of fabric inserted into a garment along a seam or cut to lengthen the free edge, and to make a garment roomier and to add a wavy edge.