2d2D means 2 Dimensional, and includes shapes like triangles, squares, rectangles, circles and more! Here we show the moost common 2D shapes. 2D Shapes. A plane or 2D shape has 2All 2D shapes can be measured by their length and width or length and heht. But remember, shapes that are 2D are completely flat. For example, the square below is a shape in 2D