Noncircular

Noncircular is an adjective used to describe objects, shapes, paths, or symmetries that are not circular. In geometry, a circle is defined as the set of all points at a fixed distance (the radius) from a given point (the center). Objects that do not satisfy this condition are called noncircular. The term is used descriptively rather than as a formal mathematical category.

Examples include polygons such as triangles and rectangles, irregular shapes, and most conic sections such as ellipses, parabolas, and hyperbolas. Note that an ellipse is a noncircular shape unless its major and minor axes are equal (in which case it becomes a circle). Noncircular shapes exhibit varying radii or lack uniform symmetry about a center.

In applied contexts, noncircular is used to describe gears with noncircular profiles, cams, shafts with noncircular cross sections, or movement paths that avoid circular arcs. Such designs can be used to modify speed, torque, or contact patterns, or to fit spatial constraints. Noncircularity can be intrinsic (a permanent property of the object) or imposed by manufacturing tolerances or deformation.

See also: circle, ellipse, polygon, conic section, geometry.