A plane shape. More detailed names depend on the shape itself.
A 2D shape with 9 sides is called a Nonagon.
Octagon
2D shapes include squares, triangles, rectangles and circles.
Square
Tetradecagon.
hexagon
Hexagon
A pentagon
Octagon
A ten-sided 2D polygon is known as a decagon.
A twenty sided, 2D figure is called an icosagon.
A nonagon is a 2D shape and there is not a 3D equivalent shape.