aether

“According to ancient and medieval science, aether, also known as the fifth element or quintessence, is the material that fills the region of the universe beyond the terrestrial sphere.”

form

“Form is a three-dimensional object with volume of height, width and depth. These objects include cubes, spheres and cylinders. Form is often used when referring to physical works of art, like sculptures, as form is connected most closely with those three-dimensional works.”