Definitions for

**"Paraboloid"**The solid generated by the rotation of a parabola about its axis; any surface of the second order whose sections by planes parallel to a given line are parabolas.

A geometric surface whose sections parallel to two co-ordinate planes are parabolic and whose sections parallel to the third plane are either elliptical or hyperbolic.

a surface having parabolic sections parallel to a single coordinate axis and elliptic sections perpendicular to that axis