noun.
A support, such as a hoop, worn beneath a skirt to extend it horizontally from the waist, used by European women in the 1500s and 1600s.
The Century Dictionary and Cyclopedia
noun.
A contrivance for extending the skirts of women's dresses, resembling the modern hooped skirt and made of ribs of whalebone run into a cloth foundation.
the GNU version of the Collaborative International Dictionary of English
noun.
A hoop skirt or hoop petticoat, or other light, elastic material, used to extend the petticoat.