What is "developable surface"

Developable \De*vel"op*a*ble\, a. Capable of being developed.
--J. Peile.

Developable surface (Math.), a surface described by a moving right line, and such that consecutive positions of the generator intersect each other. Hence, the surface can be developed into a plane.

n. A surface (in more than two dimensions, a plane is trivially developable) that can be flattened into a plane without distortion.

In mathematics, a developable surface (or torse: archaic) is a surface with zero Gaussian curvature. That is, it is a surface that can be flattened onto a plane without distortion (i.e. "stretching" or "compressing"). Conversely, it is a surface which can be made by transforming a plane (i.e. "folding", "bending", "rolling", "cutting" and/or "gluing"). In three dimensions all developable surfaces are ruled surfaces (but not vice versa). There are developable surfaces in R which are not ruled.