sandals
Slippers cut low over the foot and tied on by a criss-cross of ribbons or strings over the instep and around the ankle. They were not the open-toe summer show we know as sandals today. Any shoe that laced up the ankle was called a sandal.
The print shown is a detail from "Ball Dress," Ackermann's Repository of Arts, April 1811: "White satin sandal-slippers, tied with green ribbon round the ankle."