A rotation's a movement of an object in a circular motion. A two-dimensional object rotates around a center (or point) of rotation. A three-dimensional object rotates around a line called an axis. If the axis of rotation's within the body, the body's said to rotate upon itself, or spin—which implies relative speed and perhaps free-movement with angular momentum. A circular motion about an external point, for example the Earth about the Sun,'s called an orbit or more properly an orbital re… (More on Rotate)