There is no such shape.
you call a two dimensional shape with six sides a hexagon
a circle
A circle!!
circle
hexagon
Hexagon.
Hexagon
It is an inscribed angle.
A cyclic polygon.
It is the subtended angle of the arc
as shape with four sides is generally a squre but a group of shapes with four sides are called quadrelaterals
No name is specified but if you consider an infinite number of sides it would be indistinguishable from a circle.