Figure-eight

A figure eight is anything that is in the shape of the number 8 or the infinity symbol ∞.
Movement in the shape of a figure eight is done in ice skating, auto racing, sailing, horse riding, and dancing. Some roller coasters are shaped like a figure eight.
A figure-eight knot is a type of knot in knot theory. Another type of figure-eight knot, and the similar figure-eight loop and figure-eight bend, can be tied on a rope.