Surface whose points can all be connected by straight lines contained in the surface

Question

I don't know the mathematical term used to define a surface whose points can all be connected by staright lines contained in the surface vs cannot all be connected by straight lines contained in the surface.

My field of expertise is Computational Aerodynamics, and I'm trying to prove that a wing with a delta wing needs to be treated way differently than in the case of a sweptback wing.

This image illustrates some wings planforms. Compare all of them to the Sweptback wing. Forget about the fuselage and assume the wing is in a plane. Is there any mathematical term used for this? I can't find the answer on the internet.

Answer 1

Maybe you are looking for a Convex set?. It requires that the line segment connecting any two points of the set be contained in the set.

Answer 2

Try "developable surface".https://en.wikipedia.org/wiki/Developable_surface (Apparently that was not enough characters.)