The kolpos is the blousing of a peplos

Peplos

A peplos is a body-lengthGreek garment worn by women before 500 BC. The peplos is a tubular cloth folded inside-out from the top about halfway down, altering what was the top of the tube to the waist and the bottom of the tube to ankle-length. The garment is then gathered about the waist and the...

, chiton

Chiton

Chitons are small to large, primitive marine molluscs in the class Polyplacophora.There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura....

 or tunic

Tunic

A tunic is any of several types of clothing for the body, of various lengths reaching from the shoulders to somewhere between the hips and the ankles...

 in Ancient Greek clothing, whereby excess length of the material hangs folded over a zone

Zone (vestment)

The Zone ; occurs in Homer as a woman's girdle and can even refer to her waist itself. Classical Greek had a verb put a girdle around the loins, or "gird one's self."...

 (a narrow girdle).

The fabric of the garment was typically cut longer than the shoulder-to-floor measurement of the women or man wearing it. The excess length was dealt with at the waist (creating the kolpos) and optionally the top edge (creating the apoptygma). To create the kolpos, a zone was tied around the body below the breast (high-girdled) or at the waist (low-girdled) and excess fabric was pulled up over it. The fabric fell over the girdle so as to hide it, and was often pulled longer in back than in front. This fold was the kolpos. A second (visible) zone could be tied over the kolpos to redefine the waist, high or low. This might be hidden again by the apoptygma, the loose, folded down top of the peplos.