Of, pertaining, or relating to a cone.

Geometry. A point in a surface through which all its lines of curvature pass.

In Ellis's Stigmatic Geometry, A point whose movement in a certain plane is determined by that of another point (the index) in the same plane.

A point on a surface at which there are two tangent planes.

a point in the complex plane at which two or more branches of a function (usually an algebraic function) of a complex variable coincide.

(a) a point at which a curved surface is locally level but at which its curvature in two directions differs in sign, i.e. for a surface defined by…

Mathematics. = saddle point n. at compounds 4.