Axonometric Projection

A form of Parallel Projection in which objects are illustrated along multiple axes to reveal multiple sides of the object. Axonometric literally means “to measure along axes.”

This can be contrasted with Orthographic Projection, which depicts objects parallel to the projection plane. In Axonometric Projection, objects are always illustrated so they are not parallel to the projection plane.

The three forms of Axonometric Projection:

isometric-dimetric-trimetric

[wikipedia: Axonometric Projection]