flat diaper

Etymology
From the shape of the fabric before being folded into a diaper.

Noun

 * 1)  A makeshift cloth diaper folded from a large piece of (usually square or rectangular) absorbent fabric, such as terry (coarse cotton), which is held in place by a diaper pin or other fastener.

Usage notes

 * The fabric from which the flat diaper is folded may be called the, (especially when sewn into an already-existing diaper) or, less commonly, the.