A three dimensional object is known as a solid.
In geometry, we often categorize objects based on their dimensions. A two-dimensional object exists in a plane and has only two dimensions: length and width. Examples include circles, squares, and triangles.
On the other hand, a three-dimensional object has depth in addition to length and width, making it a solid figure. Examples of three-dimensional objects include cubes, spheres, and cylinders. The third dimension allows solids to occupy physical space, which is why we perceive them differently than flat shapes.