polar coordinates

noun[usually plural]3

1. •
   The coordinates of a point in a plane, measured as its Cartesian distance from the origin and the angle measured counterclockwise from the x-axis to a line joining the point to the origin.
2. •
   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 counterclockwise from the x-axis to this line.
3. •
   A system of coordinates using such measurements to indicate position.