1) Big ring to spin on the hips 2) Brand that became generic 3) Fad of the 1950s 4) Popular purchase in the 1950s 5) Ultra Music single 6) Wham-O brand 7) Wham-o product 
Volcanism of the Canary Islands, Spain. ... A hula hoop is a toy hoop that is twirled around the waist, limbs or neck. The modern hula hoop was invented in 1958 by Arthur K. Melin and Richard Knerr, but children and adults around the world have played with hoops, twirling, rolling and throwing them throughout history. Hula hoops for children generally measure approximately 71 centimetres (2...
[n] - plaything consisting of a tubular plastic hoop for swinging around the hips
noun plaything consisting of a tubular plastic hoop for swinging around the hips
a brand name for a tubular plastic hoop, about 4 ft. (1.2 m) in diameter, for rotating about the body by swinging the hips, used for physical exercise or in children's play: introduced in the 1950s.