Peplum is often used as another term for overskirt.
The design of the overskirt depended on the era in which it appeared, and a variety of overskirts have appeared throughout history:
Greatcoat dress—Despite the name, this garment mimicked the men’s greatcoat. It was essentially an ankle-length robe worn over a skirt. The robe could be buttoned from collar to hem, with the overskirt of the robe completely covering the petticoat. More often, the robe was left unbuttoned below the waist and the overskirt allowed to fall away on either side to reveal the petticoat. It was fashionable in the late 1700s.
Irish polonaise—Also known as a “French polonaise”, “Italian polonaise”, or “Turkish polonaise”, this garment consisted of a tight-fitting, low, squarish bodice with an overskirt. The overskirt was in a style similar to the polonaise: pleated to the bodice, bunched in the rear, and open in front. The overskirt was much longer than the petticoat beneath. It was popular in the United Kingdom from 1770 to 1775.
Italian nightgown—Also known as an “Italian robe” and “Italian polonaise”, this was an informal garment. This dress appeared in the United Kingdom from the 1750s to 1790s. The dress consisted of a stayed bodice with somewhat low-cut décolletage, sleeves that reached the elbow, skirt, and overskirt. The overskirt, in this case, was almost always of a contrasting color to the skirt and was almost as long as the skirt itself. The overskirt could be gathered and draped into a polonaise.
Mantua—This was essentially an oversized gown, popular throughout Europe from the mid-1600s to the mid-1700s. In its later configurations, the mantua featured an unstayed bodice which was joined to an overskirt. The overskirt was open in the front to reveal a highly decorative underskirt. In the rear, the overskirt was elaborately bunched, draped, and folded, at times even being cut and formed to create a short train.
Milkmaid skirt—The term originally applied to a bustle, but was also used to describe a daytime dress which first appeared in 1885. This dress consisted of a skirt with two stripes (each a different color), with an overskirt with gathers at the waist.
Pano—An ankle-length transparent overskirt worn by both men and women in Egypt between 4,000 BC and 30 BC.
Peplum basque—Essentially the lower part of a basque, but with longer extensions over the hips and strapped to the body with a belt. It was generally worn with a bodice. It appeared in the United Kingdom.