polar coordinates

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics The coordinates of a point in a plane, measured as its Cartesian distance from the origin and the angle measured anticlockwise/counterclockwise from the x-axis to a line joining the point to the origin.
• noun mathematics The coordinates of a point in three-dimensional space, measured as its Cartesian distance from the origin, the angle measured from the z-axis to a line joining the point to the origin, and the angle measured anticlockwise from the x-axis to this line.