figure of eight 
(North American figure eight)
noun
An object or movement having the shape of the number eight: the humpback whale described a figure of eight around a shoal of fish [as modifier]: a figure-of-eight knot...
- The cord symbolises the love and friendship, that binds the couple, the figure eight shape represents the infinite nature of matrimony.
- Birthdays and namedays call for a saffron-scented bread made of yeast dough with dried fruits into the shape of a figure eight and decorated with flowers.
- The tip of her finger glowed, and she traced a shape in the air - a figure eight with a vertical line running down its middle.