An octagon
cube
Well, 2-D shape is a square, or a quadrilateral
a heptigon
A shape with 7 sides is a heptagon
A shape with three sides is a triangle.
you call a two dimensional shape with six sides a hexagon
Triangle is a shape with three sides.
A shape with 8 sides is an octagon.
A regular shape.
a shape with nine sides is called nonagon
There is no such shape.