[[File:Historical Hoopskirts.jpg|thumb|Top: Minoan statuette, 1600 BCE. Verdugada, 1470s<br>
Bottom: Farthingale, 1600. Hoop or pannier, 1750–80.]]
thumb|Cage crinoline with steel hoops, 1865. LACMA M.2007.211.380
A hoop skirt or hoopskirt is a women's undergarment worn in various periods to hold the skirt extended into a fashionable shape.
It originated as a modest-sized mechanism for holding long skirts away from one's legs, to stay cooler in hot climates and to keep from tripping on the skirt during various activities. Small hoops might be worn by farmers and while working in the garden. Hoops were then adopted as a fashion item, and the size and scale of the hoops grew in grandeur, especially during the mid-nineteenth century transition from the 1850s to the 1860s. As the society of consumerism evolved, the roles of men and women changed and so did their dress.
In the mid-19th century, the fashionable silhouette was a small waist with large, dome-shaped skirts. More and more petticoats were added to make the skirts appear even larger. When the circular crinoline came out in 1856, it was a revelation not only of technology but of convenience for women.
The mania for large bell-shaped skirts phased out through the mid-1860s and slowly shifted to emphasize volume in the posterior. The crinolette came into fashion, which was basically a narrow crinoline with a flat front and cage hoops in the back. The crinoline of the mid-19th century was constructed from collapsible steel hoops. This allowed for easy storage and increased agility for the wearer.