Curvilinear coordinate systems are a means of describing an object/point's position based on angle and distance from the origin. For example, polar coordinates are Curvilinear coordinates for R2 (2D space). Spherical coordinates are Curvilinear coordinates for R3 (3D space) If you need to know more:

http://en.wikipedia.org/wiki/Curvilinear_coordinates

english?

The figure was a curvilinear figure.

Harry Melvin Shoemaker has written:

'A generalized equation of the vibrating membrane expressed in curvilinear coordinates' -- subject(s): Vibration

Curvilinear seems to fit the description of a cone