Examples from the Web for quadric
Every conic which has five points in common with a quadric surface lies on the surface.
Instead of a circle or sphere we may take any conic or quadric.
Every plane which cuts a quadric surface in a line-pair is a tangent plane.
The surface itself is therefore called a quadric surface, or a surface of the second order.
If through one point on a quadric surface no line on the surface can be drawn, then the surface contains no lines.