A hoop skirt or hoopskirt is a women's undergarment worn in various periods to hold the skirt extended into a fashionable shape.

Hoop skirts typically consist of a fabric petticoat with casings to hold a stiffening material, variously rope, osiers, whalebone, steel or nylon.

Lightweight hoop skirts, ususally with nylon hoops, are worn today under very full-skirted wedding gowns.

See also:

Farthingale (sixteenth century)

Panniers (eighteenth century)

Crinoline (nineteenth century)

Bustle (nineteenth century)