MIL-STD-31000B : DOD Standard Practice Techincal Data Packages
Geometry consists of the mathematical description of individual part surfaces. Modern CAD systems employ what is called the boundary representation method for describing model geometry. Boundary representations consist of curves, surfaces, edges, and faces. In a valid model, the faces meet at the edges to form a closed volume.
See Also:
Part, Surface, CAD, Model
Alternate Definitions:

MIL-STD-31000B - The surface shape of a mechanical part.