The edge of a 3D shape is called an "edge." It is the line segment where two faces of the shape meet. In geometric terms, an edge is one of the fundamental components that define the structure of polyhedra and other solid figures.
edge
A 3D semi circle
A 3D shape with one edge is known as a "curved surface" or more specifically, a "cylinder" with its top and bottom bases removed, resulting in a shape resembling a "circular loop" or "moebius strip." However, in strict geometric terms, conventional polyhedra cannot exist with just one edge. The concept of a 3D shape having only one edge typically refers to more abstract or non-Euclidean geometries.
A cone perhaps?
A cone.
edge
An edge.
A 3D semi circle
An impossible shape!
Cylinder
CONE
A cone perhaps?
A cone.
it if called a edge for a 3D shape
you call it a edge
2D shape = Decagon 3D shape = Decahedron
nonahedron