Wikipedia
Spool heel
A spool heel is a heel that is wide at the top and bottom and narrower in the middle, so resembling a cotton reel. Spool heels were fashionable in Europe during the Baroque and Rococo periods. Other periods of popularity include the 1860s and the 1950s. Spool heels are characterized by an hourglass shaped heel .i.e., thick at both ends and thin in the middle. This look has been popularized by John Fluevog.
A low spool heel has a small distinctive flare at the heel bottom. Higher spool heels are close to resembling a stilleto heel, but with a flare at the bottom.
Spool heels provide a lot of comfort of the wearer and are considered a more practical heeled shoe option.