|The Simple English Wiktionary has a definition for: shape.|
A shape is a geometric figure that can be described with mathematics. One way to classify shapes is to describe a bigger shape that the shape fits inside of. For example, two-dimensional shapes like circles will fit inside of a flat plane. Three-dimensional objects like cubes will not fit inside of a plane, because they are not flat.
Two shapes are said to be equal, if one can be changed into the other by spinning, moving, growing bigger, shrinking, or more than one of these in a combo
[change] Ordinary shapes
[change] 2D shapes
These are two-dimensional shapes or flat plane geometry shapes. Their sides are made of straight or curved lines. They can have any number of sides. Plane figures made of lines are called polygons. Triangles and squares are examples of polygons.