(also US trademark Hula-Hoop)
Definition of hula hoop
a large hoop spun round the body by gyrating the hips, for play or exercise.
verb (hula-hoop) [no object] (usually as noun hula-hooping)
spin a hula hoop round the body by gyrating the hips: hula-hooping is back, and adults, rather than children, are driving the new craze