Roundness refers to the degree to which an object's surface deviates from a circular shape, and is usually used to describe the surface characteristics of a cylinder or cone. Roundness is usually expressed as a deviation in diameter or radius and is a measure of the roundness of an object's surface.
Straightness refers to the degree to which the surface of an object deviates from a straight line, and is used to describe the characteristics of a plane or straight line. Straightness is usually expressed as a distance deviation and is a measure of the straightness of an object's surface.
Circular runout refers to the irregular motion of a rotating object on a bearing or other support structure and is often required to be controlled in high-precision rotating machinery. Circular runout causes erratic or irregular motion of an object on an axis of rotation as it rotates.
