There can be no such shape. If there were a shape with n flat surfaces, then if you sliced off one vertex, you would have a shape with n+1 flat surfaces. So it is always possible to add one more flat surface.
Cylinder
A sphere
A sphere
There are two definitions for 'cuboid', but they both describe a shape with six flat surfaces (or 'faces').
There can be no such shape. If there were a shape with n flat surfaces, then if you sliced off one vertex, you would have a shape with n+1 flat surfaces. So it is always possible to add one more flat surface.
a rectangle
cube There are a great many solid shapes that have only flat surfaces.
A cube
a cylinder
It is a cube or a cuboid
cylinder
Cylinder
A sphere
A sphere
There is no such shape.
There are two definitions for 'cuboid', but they both describe a shape with six flat surfaces (or 'faces').