Quadric

Webster's Dictionary of the English Language

·adj Of or pertaining to the second degree.

II. Quadric ·noun A quantic of the second degree. ·see Quantic.

III. Quadric ·noun A surface whose equation in three variables is of the second degree. Spheres, spheroids, ellipsoids, paraboloids, hyperboloids, also cones and cylinders with circular bases, are quadrics.